Thermal Submodeling in ANSYS Workbench Mechanical 15.0

If you've been following The Focus for a long time, you may recall my prior article about submodeling using ANSYS Mechanical APDL, which was a 'sub' model of a submarine.  The article, from 2006, begins on page 2 at this link:

Also, Eric Miller here at PADT wrote a Focus blog entry on the new-at-14.5 submodeling capability in ANSYS Workbench Mechanical.

Since both of those articles were about structural submodeling, I decided it was time we published a blog entry on how to perform submodeling in ANSYS Mechanical for thermal simulations.

Submodeling is a technique whereby we can obtain more accurate results in a small, detailed portion of a large model without having to build an incredibly refined and detailed finite element model of our complete system.  In short, we map boundary conditions onto a 'chunk' of interest that is a subset of our full model so that we can solve that 'chunk' in more detail.  Typically we mesh the 'chunk' with a much finer mesh than was used in the original model, and sometimes we add more detail such as geometric features that didn't exist in the original model like fillets.

The ANSYS Workbench Project Schematic for a thermal solution involving submodeling looks like this:


Figure 1 – Thermal Submodeling Project Schematic

Note that in the project schematic, the links are automatically established when we setup the submodel after completing the analysis on the coarse model as we shall see below.

First, here is the geometry of the coarse model.  It's a simple set of cooling fins.  In this idealized model, no fillets have been modeled between the fins and the block.


Figure 2 – Coarse Model Geometry, Idealized without Fillets

The boundary conditions consisted of a heat flux due to a  thermal source on the base face and convection to ambient air on the cooling fin surfaces.  The heat flux was setup to vary over the course of 3 load steps as follows:

Load Step        Heat Flux (BTU/s*in^2)

            1                      0.2

            2                      0.5

            3                      0.005

Thus, the maximum heat going into the system occurs in load step 2, corresponding to 'time' 2.0 in this steady state analysis.


Figure 3 – Coarse Model Boundary Conditions – Heat Flux and Convection

The coarse model is meshed with relatively large elements in this case.  The mesh refinement for a production model should be sufficient to adequately capture the fields of interest in the locations of interest.  After solving, the temperature results show a max temperature at the base where the heat flux is applied, transitioning to the minimum temperature on the cooling fins where convection is removing heat.


Figure 4 – Coarse Model Mesh and Temperature Results for Load Step 2

Our task now is to calculate the temperature in one of these fins with more accuracy.  We will use a finer mesh and also add fillets between the fin and base.  For this example, I isolated one fin in ANSYS DesignModeler, did some slicing, and added a fillet on either side of the base of the fin of interest.


Figure 5 – Fine Model (Submodel) Isolated Fin Geometry and Mesh, Including Fillets at Base


ANSYS requires that the submodel lie in the exact geometric position as it would in the coarse model, so it's a good idea to overlay our fine model geometry onto the coarse model to verify the positioning.


Figure 6 – Submodel and Coarse Model Overlaid


Figure 7 – Submodel and Coarse Model Overlaid, Showing Addition of Fillet

The next step is to insert the submodel geometry as a stand-alone geometry block in the Project Schematic which already contains the coarse model, as shown in figure 8.  A new Steady-State Thermal analysis is then dragged and dropped onto the geometry block containing the submodel geometry.


Figure 8 – Submodel Geometry Added to Project Schematic, New Steady-State Thermal System Dragged and Dropped onto Submodel Geometry


Next, we drag and drop the Engineering Data cell from the coarse model to the Engineering Data cell in the submodel block.  This will establish a link so that the material properties will be shared.


Figure 9 – Drag and Drop Engineering Data from Coarse Model to Submodel

The final needed link is established by dragging and dropping the Solution cell from the coarse model onto the Setup cell in the submodel.  This step causes ANSYS to recognize that we are performing submodeling, and in fact this will cause a Submodeling branch to appear in the outline tree in the Mechanical window for the submodel.


Figure 10 – Solution Cell Dragged and Dropped from Coarse Model to Submodel Setup Cell

After opening the Mechanical editor for the submodel block, we can see that the Submodeling branch has automatically been added to the tree.


Figure 11 – Submodeling Branch Automatically Added to Outline Tree

After meshing the submodel I specified that all three load steps should have their temperature data mapped to the submodel from the coarse model.  This was done in the Details view for the Imported Temperature branch, by setting Source Time to All.


Figure 12 – Set Imported Temperature Source Time to All to Ensure All Loads Steps Are Mapped

Next I selected the four faces that make up the cut boundaries in the submodel and applied those to the geometry selection for Imported Temperature.


Figure 13 – Cut Boundary Faces Selected for Imported Temperature


As mentioned above, the Imported Temperature details were set to read in all load steps by setting Source Time to All.  The Imported Temperature branch can now be right-clicked and the resulting imported temperatures viewed.  I also inserted a Validation branch which we will look at after solving.


Figure 14 – Setting Source Time to All, Viewing Imported Temperature on Submodel

Any other loads that need to be applied to the submodel are added as well.  For this model, it's convection on the large faces of the fin that are exposed to ambient air.


Figure 15 – Submodel Convection Load on Fin Exposed Faces

Since there are three load steps in the coarse model and we told ANSYS to map results from all time points, I set the number of steps to three in Analysis Settings, then solved the submodel.  Results are available for all three load steps.


Figure 16 – Submodel Temperature Results for Step 2 (Highest Heat Flux Value in Coarse Model)

Regarding the Validation item under the Imported Temperature branch, this is probably best added after the solution is done.  In my case I had to clear it and recalculate it.  Validation can display either an absolute or relative (percent difference) plot on the nodes at which loads were imported.  Figure 17 shows the relative difference plot, which maxes out at about 6%.  The validation information as well as mapping techniques are described in the ANSYS Help.


Figure 17 – Submodel Imported Temperature Validation Plot – Percent Difference on Mapped Nodes

Looking at the coarse model and submodel results side by side, we see good agreement in the calculated temperatures.  The temperature in the fillets shows a nice, smooth gradient.


Figure 18 – Coarse and Submodel Temperature Results Showing Good Agreement

Hopefully this explanation will be helpful to you if you have a need to perform submodeling in a thermal simulation in ANSYS.  There is a Thermal Submodeling Workflow section in the ANSYS 15.0 Help in the Mechanical User's Guide that you may find helpful as well.




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Turkey, Team Building, and Spaghetti Towers: PADT’s Turkey Bowl 2014


[EDITOR’S NOTE:  This was written some time ago and was set to automatically go out. But I just found it stuck in the “pending” folder.  So late, but here it is]  

It has been a great 20th anniversary year for PADT.  And we decided to close it out with some fun.  Now, if you know engineers, getting them to take part in any team building event is tough. And many of our employees came to PADT to get away from such things. The phrase "team building" causes a Pavlovian eye roll.  As we discussed options for November, we looked at a lot of activities. When we settled on doing an event that not only involved teams, but also color coded shirts, puzzles, and (gasp) a lean towards being healthier I said "we should try it, but it probably won't work" and hoped to be proven wrong. Even with the help of the great folks at Physix, I didn't have high hopes. But you don't know until you try.

I was proven wrong. 

Kickoff: Halloween and Pumpkin Launching

We started with a kickoff event on Halloween, which was nice enough to be on a Friday this year. In the past we have carved pumpkins and built a dry-ice pumpkin mortar.  This year we fed everyone to get them in a good mood and then put them in teams.  After some trivia contests we moved over the the first event – a pumpkin slingshot.

We finished up the kickoff event with rules and a list of ways to get points:  go to lunch with team mates, go for a hike, attend a class at Physix, get a fitness assessment, lose weight, answer the weekly quiz, and walk.  The easiest way to get points was to keep track of your step count.  

Three Weeks of Getting Points

The next three weeks were fun. Different teams approached things differently. Some opted to lunch together, often.

yhsfgn yhfgsdhsfh yfghdfhg ttertfg ttasn hhhhhhhhhhhhhh hhhhhhh ffffas fasdftrt fafrtyy asdfgg yujghj

Others did a fitness assessment or attended a class.  One team even tried to take a hike… on Photoshop:


Funny how their picture on Camelback Mountain looks a lot like their lunch picture…  

After a bit of a kerfuffle on Body Mass Index results from the fitness assessment, we held a brown bag seminar by the lake.  The reason why Physix is a great match for PADT is that their approach to health is science and fact based.  No chakra alignment here.  So Shannon came armed with statistics, studies, and fancy measuring devices with dials on them that we could write down numbers from.


There was also a weight loss competition.  Points for every pound lost. There are and will not be pictures from that portion of the event. But we can share that some people dropped a few pounds over the three week period, and some more than a few.  

Turkey and Contests 

At the end of the three weeks we gathered together again to take part in our annual Thanksgiving Feast, and compete to win some additional points for our teams.


We started with a plank contest. Expecting 5 or so people to participate, maybe one from each team. Everyone gave it a shot:


Most people lasted a minute, then they started to drop.  


A ton of people lasted to 2 minutes, then 3, then 4.  6 people were holding at 4:30.


Purple had a strong showing, Renee lasting past 5 minutes.  Clinton held strong for purple.  Don, and Demola held on for Orange and Black.


In the end, Demola won a ton of points for his team, lasting past 6 minutes.  

Next we tried a relay event that involved passing a ball over our heads and taking a step, then running to the back, then passing… what was that again. It took us a while to figure it out.  In hindsight, we should have created a process diagram before the event.  


But Green and Black figured it out and charged to the finish line… not even stopping when one competitor stumbled.  No one left behind, as long as they have the right shirt color.

Inside, we had a timed puzzle building event. It got kind of nasty when the teams realized that each team had two pieces from another puzzle. People get aggressive when points are on the line.  There may have been some hiding, there may have been some prying of fingers open.

feverish puzzle activity

The last event was to build a tower out of spaghetti, string, tape, and a marshmallow. Whoever got their marshmallow the highest got the points.  Four of the teams built tripods and went for height.


Two teams figured out that spaghetti bends and breaks.  Blue felt that building a box was better. I guess that is thinking outside the box?


But the winner was a combination of tripod and "stoutness."  Green figured it out:


There was a dessert contest as well. I grudgingly mention it because my dessert didn't make it into the finals… but I'm not bitter, not at all.

dessert contest

After that we all went back to work while the PADT HR and Physix teams summed up all the points and figured out who won.  

Green, thanks to their tower, squeaked into third place:


Some were happier than others about the competition.

Second place was won by the superior team, and we would have won if my dessert had been in the finals:


And the winners were the Black Team.  


You have to admit, they do look pretty confident.

What we Learned 

Overall, the three weeks were a nice distraction from a very busy period.  Some people that would not have normally spent time together, did. Some people learned a bit about fitness or nutrition that they didn't know before. A lot of people walked a lot more.  

We also learned a couple of lessons:

  1. You can have a positive and constructive team building event at a company that is kind of wired to go against such corporate group-think activities.

  2. Not everyone wants to participate. That's OK and it is no reason why those that do can't have fun.  And you can find small ways for people to take part.

  3. Some people are REALLY competitive. 

  4. The average core strength at PADT is stronger than we thought.

  5. The breath mints we got to combat coffee breath are 50 calories, and the average person has to walk around 500 steps to burn them off. 

  6. If you don't take these things too seriously, they can be fun and a nice break.

  7. PADT's employees are clever. They tried to get points for waking up in the morning and mouse clicks.  You have seen the Photoshop picture. They also wanted to pass off the PADT Medical skeleton as Don Pegg after his diet.  It didn't work.


For those of you who are thinking of doing a similar event at your company, some key words of advice:

  1. Bring in someone to help that is a good fit for your culture. Don't try and fit a standard or large company approach to a small or medium company.  Find someone that gets you and maybe pushes your organization a bit further than you would push it on your own.

  2. Keep it short, keep it simple.

  3. Don't let the negative people drag it down. You will have some people that this is not a good fit for. If you try and please them, they will still be unhappy and it will lesson the event for others.  Just accept that not everyone will be on-board and move on.

  4. Place your tongue firmly in your cheek.  If you take these things too seriously, they will fail.  Make some fun of yourselves and the activity, it takes that edge off.


If you do it right, you might even get engineers to touch each other.  

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The Real Revolution in 3D Printing: It’s Normal

3D-printed-printerReading through my email this morning I saw an update from the "maker" site Instructables and I glanced at it quickly: "floating bed, how to make a sword, that's cool, 3D printable printer, folding chair charcoal forge, what?, parachord hammer holder, just buy one, duh, blah, blah, blah how do people have time for this… wait, 3D printable printer?" CLICK.  

So this 17 year old kid used his 3D Printer, an arduino board and parts he scrounged from old DVD drives to make a 3D Printer. Read about it here.  This kid, wootin24, designed and built an X, Y, Z positioning device that could be fited with a dremel tool to be a CNC machine, or an extruder to be a 3D Printer.  No CAD experience, no formal engineering training, just a smart person.  And the ad that popped up on the side of the how-to this kid wrote was for a Dremel 3D Printer, available at Home Depot. Not some kickstarter funded rehash of an opensource printer, Dremel. The big guys.  As I was feeling bad about how I spent my time when I was 17 (I'm not going to go there but I never did become a the backup bass player for Rush nor did I get a second date from T—–) and starting to worry about how systems from very capable companies like Dremel will impact our sales of Stratasys equipment, I realized that the true revolution in 3D printing happened and most of us involved day-to-day in the industry didn't even notice.  

3D Printing is Now Normal

When a revolutionary technology comes out there is a lot of hoopla and press. Tons of people start jumping on the bandwagon and your Aunt's friend in Topeka is sending you links on Facebook about 3D Printing and how it is "going to change everything."  Do not get me started on how 3D Printing is not new, we've been doing it at PADT for over 20 years, and certainly do not ask about the "3D printed gun.  The false-newness and fear-mongering stories are what the mainstream press picked up on. The good news is that the hype got the word out. And then smart people like this kid and the engineers at Dremel said "hmmm, that is useful. I can do something with this" and boom, the real revolution happened.  

After all these years this tool that was really a special tool used when needed, has become just another screwdriver in the toolbox.  A standard part of the process it is something most engineers understand well, and a majority of non-engineers are aware of. When we first started showing people our SLA machine back in the 90's they would either not understand what they were looking at or become flabergasted and amazed, treating it more like a magic box than a fairly simple additive curing system.  Now when we give tours we hear "that one looks like the one we have in our office" or "oh yea, an Objet, I'd love to trade my older system in for one of those." And the dreaded "oh, we have three of these in our robotics lab at school, do you have anything interesting?"  

So What

There is a lot of power in 3D Printing.  That is the real reason why the technology has blossomed as it has.  The power of 3D Printing is that it lets you make physical objects without special equipment or knowledge, the laser printer of manufacturing. However, as long as the tool is treated as something to be used in special cases or as a mystical new magic bullet, it will not be used correctly.  Now that it is mainstream, the use of additive manufacturing becomes mainstream and the power it brings to the table can be fully realized.  We see this every day at PADT. Product managers have "3D Printed Prototypes" as a standard line item in their budget templates.  Customers are increasingly talking about going back to their current product lines and identifying parts that are machined, injection molded, or cast and determining which can be replaced by 3D printed parts.  And most importantly, the supply chain and quality people are sniffing around and starting to make paperwork to control and manage 3D Printed components.  

As proponents of the technology since the early days, we could not be happier than when we see a check box for "Created with additive manufacturing" on a quality form. When it becomes part of the bureaucracy, the revolution has truly happened. 

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Customer in the News: Soitec Sets Record for Solar Cell Efficiency at 46%

soitecWe noticed that customer and neighbor Soitec Phoenix Labs had a great writeup in the AZ Republic. Their substrate technology was used to make a multijunction solar cell for use with conentrated solar, delivering an amazing 46% efficiency. The standard right now in the mid to low 20% for single junction, the most common technology available. The article actually does a pretty good job of explaining the technology, why Soitec has something special, and some insight into their LED technology as well.

A big congrats to the team and we can not wait to hear when you break 50%!

They have a great video on their CPV efforts on their website.

Soitec is a french company that purchased GaNotec a few years back.  Their Phoenix Labs is across the lake in the ASU Research Park in the ASU MacroTechnology Works building and PADT has provided a variety of services to the company since it started as GaNotec.  We have worked with many of their employees at other Semiconductor Equipment companies before GaNotec was founded. 

Congrats to everyone!


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Press Release: Dedicated 3D Scanning Added to Round Out PADT’s Scanning Solutions


PADT has been offering 3D Scanning solutions for some time. Over time the company has added the sale of 3D Scanning hardware and software, training for 3D Scaning, and limited 3D Scanning services.  With the addition of a full time scanning engineer, PADT is now able to offer deciated scanning servcies to our customers.

Ademola Falada joins our team from Minnesota where he worked for a scanner manufacturer, CGI, for two years after graduating with an engineering degree from the University of Minnesota.  He brings extensive knowledge of scanning equipment and the scanning process.  Since joining PADT in the late summer, he has been providing limited services to our existing customers as he builds up our scanning capability and puts everything needed to provide a world class service in place.  He will be assisted by engineers and technicians that have been providing scanning on a part time basis in the past.


By offering optical and cross sectional scanning, PADT can provide a more accurate solution to a broader range of customers.  

Read the press release on this expanded service below


You can also review our scanning services on our website

Or simply email us at or call 480.813.4884 and our team will be more than happy to explain what we can do and provide you with a quote. 


Press Release:

Dedicated 3D Scanning Added to Round Out PADT’s Scanning Solutions 

PADT now has a full time engineer and equipment dedicated to providing 3D Scanning services to customers.  Coupled with the sales and support of 3D scanners and software, PADT can now offer a complete solution to its growing number of scanning customers. 

Tempe, AZ – January 8, 2015 – Phoenix Analysis & Design Technologies, Inc. (PADT, Inc.), the Southwest’s largest provider of simulation, product development, and rapid prototyping services and products, is pleased to announce the addition of complete 3D part scanning to our services offering.  Based on growing customer requests, PADT has invested in equipment, software, and personnel to provide a dedicated resource in this area.  The company has been providing scanning as a service for many years, but on a part time basis when staff was free and customers could not find another resource.  PADT’s 3D Printing sales team has also been selling scanners and scanning software for over three years.  Bringing someone on board to focus on this critical need in product development was the next logical step.

3D Scanning is used by engineers to take a part in the real world and measure it accurately in order to get a model of the part on a computer.  This is done using a variety of technologies including lasers, patterned light, and high resolution pictures. The technology is used in product development to capture geometry of existing parts to reproduce (reverse engineering) them or design parts that attach or interact with them. It can also be used to inspect manufactured parts.

Ademola Falada joins our team from Minnesota where he worked for a scanner manufacturer, CGI, for two years after graduating with an engineering degree from the University of Minnesota.  He brings extensive knowledge of scanning equipment and the scanning process.  Since joining PADT in the late summer, he has been providing limited services to our existing customers as he builds up our scanning capability and puts everything needed to provide a world class service in place.  He will be assisted by engineers and technicians that have been providing scanning on a part time basis in the past.

“We are now ready to open our doors wide to customers who need accurate, timely, and useful scanning of their parts.” Commented Rey Chu, one of PADT’s owners and the Principal responsible for the company’s manufacturing services. “We never felt that we could deliver the level of service that customers expect from PADT until we had enough equipment and a dedicated engineer. We are there now.”

The scanning lab consists of two CGI Cross Sectional Scanners for high fidelity scanning of complex plastic parts with internal features, a Geomagic Capture blue light scanner, and a Steinbichler high resolution blue light scanner currently under evaluation. This combination of equipment is matched with the full suite of Geomagic scanning software to provide inspection data, cleaned point clouds, tessellated solids (STL), or usable CAD models. 

Customers who are interested in having parts scanned, or who want to learn more about the service, can contact the team at 480.813.4884 or 

Phoenix Analysis and Design Technologies, Inc. (PADT) is an engineering service company that focuses on helping customers who develop physical products by providing Numerical Simulation, Product Development, and Rapid Prototyping products and services. PADT’s worldwide reputation for technical excellence and an experienced staff is based on its proven record of building long term win-win partnerships with vendors and customers. Since its establishment in 1994, companies have relied on PADT because “We Make Innovation Work.“  With over 75 employees, PADT services customers from its headquarters at the Arizona State University Research Park in Tempe, Arizona, its Littleton, Colorado office, Albuquerque, New Mexico office, and Murray, Utah office, as well as through staff members located around the country. More information on PADT can be found at

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Serial and Parallel ANSYS Mechanical APDL Simulations

ANSYS-APDL-Macro-PeDALThere are times when you want to study the effects of varying parameters.  If you have an existing MAPDL script that is parameterized, the following procedure will allow you to easily run many variations in an organized manner. 

Let’s assume a parameterized MAPDL macro called build_solve that does something you want to simulate many times and has 2 variables called power and scale which are set with argument 1 and 2 respectively.  Running this macro with the classic interface, with power=30 and scale=2.5 would look like this:


Next, create a MAPDL macro to launch all of the simulations.  This script could be named control.mac.  The first thing to do here is to create arrays of your parameters and assign values to them.  This example will vary power and scale.  Here are the arrays of values that will be passed to build_solve:





Most of the control.mac commands will be put inside of nested *do loops.  There will be a *do loop for each of parameters being varied.



Next, use *cfopen to set up the arguments to be passed to build_solve.  Each time through the *do loops will create a new run1.mac







One of the key features of this approach is to run anywhere and build directories below the working directory.  Use the /inquire command to store the current directory name.


Use *cfopen to create a string that will be used for the directory name.  By using the variables as part of the string, the directories will have unique names.  A time or date stamp could also be included in this string.  This macro is executed immediately to create the string dirnam for use in the commands subsequently.







Eventually, the resulting directory structure will look something like the image below.  Each directory will contain a separate simulation with the arguments of power and scale set respectively.


The last *cfopen creates a windows batch file which will (when executed)

  1. Create the new directory

  2. Copy all of the macro files from the working directory into the new directory (including run1.mac)

  3. Change into the new directory using CD

  4. Launch ansys in batch mode, in this case using a gpu and 12 cpus, using the run1.mac input and outputting to f.out

  5. Change back to the working directory (ready to do it all again)

The code for the windows batch file is:





COPY *.mac "%C\%S"


CD "%C\%S"


"C:\Program Files\ANSYS Inc\v150\ansys\bin\winx64\ansys150" -b -acc nvidia -np 12 -i run1.mac -o f.out


CD "%C"


The last step is to run the windows batch file.  /sys is used to make this system call.  If the simulation is not well parallelized and you have enough licenses available, run the simulations in low priority mode immediately.  This will launch all of your simulations in parallel:

  • /sys,start /b /low rfile.bat

If the model is well parallelized (in other words, it will use your system’s gpu/cpus/RAM efficiently) or you only have 1 license available, launch the batch files in high priority mode and use the /wait option which will insure that windows waits for the job to finish before launching the next simulation.

  • /sys,start /b /high /wait rfile.bat

You can download and view the examples control.mac and build_solve.mac from this zip file:

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ANSYS 2015 Hall of Fame Announced – Los Alamos National Labs and SynCardia Models are Finalists


Every year for a while now ANSYS, Inc. has chosen models made by users of the ANSYS software tools for their Hall of Fame.  This year had some very cool models across CFD, Structural, and Electromagnetic – including some great Multiphysics applications. Visit the ANSYS website to see all the winners here.

The three commercial winers of "Best in Show" were varied but powerful examples of how simulation can be used to improve performance and reliability of products:


Andritz Hydro used ANSYS Mechanical to model their assemblies to see if replacing welds with bolted joints would reduce weight and cost while keeping reliability.  They used sub-modeling, bolted joints, and contact.  

BRP used ANSSY CFX, ICEM CFD, and Mechanical to capture the forces caused by cavitation on their outboard marine engine. This engine pushes a boat at 75MPH (!!!) through the water, so yes, they get cavitation.  They used ICEM CFD for meshing, CFX to predict the cavitation and capture the cavitation loading, and Mechanical to see how the loading impacted the gear train and shafts. They were able to obitmize the desgin quickly using this process.

Spinologics used ANSYS Mechanical APDL to model the process of using a rod to straighten a deformed spine (scoliosis). They use the scriptability of the APDL to automate the creation of the models.  Very cool stuff.  Check out the video on the link.

We also want to mention two customers that were involved as Finalists.  

syncardia-heartSynCardia is often mentioned in this blog because, well, they make a frick'n artificial heart that saves lives every day.  We modeled an early iteration on the heart as a multiphysic problem probobly 5 or 6 years ago, it could have been longer ago. More recently Stony Brook University and the University of Arizona did a much more detailed model in ANSYS Fluent that looks at not just pressure and velocity, but Platelet dispersion patterns in the artificial heart.  Check out the video here:

2015-lanl-bgLos Alamos National Labs is another long time PADT customer and we were fortunate enough to be involved in the study that was recognized as a finalist. They used ANSYS Fluent to model something called vortex-induced motion or VIM in off-shore oil rigs.  Basically waves hit the platform and create these big swirling vortices.  These in turn put loads on the structure that can sometimes be very large.  The purpose of this study was to find a way to accurate predict VIM with simulation so they could then evaluate various solutions. A true Fluid-Solid Interaction (FSI) and because of the size of the structures and all that turbulence, High Performance Computing (HPC) problem. We hope to publish a paper on some related work this year… watch this space for more.

 This competition is a great way to see what others are doing, and if you submit your models, to show off what you have done.  Contact your ANSYS rep to learn more or drop us a note.


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ANSYS Icepak: Diverging Residuals, Find and Fix the Problem!

Over the past week I have found myself dealing with a stubborn natural convection ANSYS Icepak model with convergence plots that would have been more aptly named divergence plots that looked like this:


In this post I’m going to show you the process I went through to find and fix my problem.

First, a few things to know about Icepak:

  • Many of the problems associated with your Icepak model are very likely mesh related.

  • If the bad elements are in a solid, you are probably OK, but if they are in the fluid, watch out!!

So, what is the conclusion? I have a mesh problem.

Second, how do you find the problem?

According to the above “convergence” plot, the continuity equation is diverging (or to my frustrated, on-a-deadline mind, it was GOING CRAZY). Well, a diverging continuity equation indicates that I have a conservation of mass problem. After consulting with one of my more experienced colleagues, Clinton Smith, he suggested that I do the following to work towards pin-pointing the problem:

  • Plot the gravity direction velocity (in my case, this was Uy)

  • Look for the Minimum and Maximum Uy locations in the model

Plotting Uy along a cut plane produced this:



As Clinton thought, plotting Uy instantly showed me the section of my model that was producing un-physical results. Next, I looked for the maximum and minimum velocity locations because this would further show me problems.



Next, I need to determine why this area of my model is the problem. Like I said above, it is likely a mesh problem. In the Mesh Control panel under the Quality tab checking the Face alignment values often help to locate very bad elements:


Clicking on the pink block above displays the elements in the graphics window and it was instantly obvious that my problem was due to distorted elements in my area of interest:



When I look at these elements with a perspective of my model geometry I see that the elements are obviously in the fluid domain:



I have found my problem.

Third, how do I fix the problem? Well, the location of my bad elements happens to lie on a CAD body in Icepak. This means that I am limited in my ability to control the mesh on the actual body. So, though there are likely multiple ways that this problem could be solved, I had the idea to create an air block in the area above that I could much more easily control from a meshing perspective. Having a real Icepak primitive in that space would force the mesher to conform to the boundary of the CAD body.


Like I thought, the air block worked!


I should note that in order to get the mesh to conform exactly, I had to put the air block into its own meshed-separately assembly. And now my residuals look much better!



  • Diverging continuity residuals indicate a conservation of mass problem

  • Plot velocities to locate problem region

  • Plot min/max velocity to further identify problem

  • If bad elements are in the fluid region, they must be fixed

  • Consider creating an air block in the region of interest to more finely control the mesh

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Christmas Right-Left Gift Exchange Story: Fairy Tail Style

Left-Right-Christmas-Story-2014For our Christmas parties at PADT we generally have over 40 employees so a traditional secret Santa gift exchange takes to long. So a couple of years ago we downloaded a right-left gift exchange story from the internet and it was a big hit. We ran out of stories on the internet, so we started writing our own, usually in some sort of over-the-top style.  This year we have a cationary fairy tail. Here is how it works. 

Everyone gets their gift and forms a big circle in the middle of the room.  Someone with a strong voice reads the story and every time the world LEFT is read, everyone passes the package they have to the left. Every time the world RIGHT is read, everyone passes the package they have to their right.  You should pause a bit at each LEFT/RIGHT to give people a chance to pass.  

You can find previous years stories here:

– Film Noir Christmas
– Science Fiction Christmas
– Romance Christmas

The Wooden Horse

In a village, that sits on the left bank of the river Dreamwald, there is a good and generous family, the Leftmulds. The father is the last barrel wright left in the duchy of Cornwil-o-day-leffon.  He has a wife, two gorgeous twin daughters, and a son name… Albert.  Albert was willful and spoiled.  He thought he was always right and he always wanted what he wanted right now. 

One day, about right when the cows needed to come in from pasture, Albert stormed in to his father’s workshop, walked right up to his father, and said:  You have left me no choice but to go on strike.  I demand you make me a wooden horse toy right now.  

“Albert” his father said “You left the door open. Please close it.”

Albert replied: “I don’t care if I left the door open, you promised me a horse and I want it now. “

His father said “I told you, when you clean the right side of the barn, and there is no mud left on the floor, and there is no hay left outside, I will give you your horse”

“I hate you!  I wish you had left me with the stork!  I’m leaving right now”

And with that, he stormed out.  All is father said was “You still left the door open my son. Something is not… correct with you”

Albert ran from the village. Right past the mill, right past the well, and right out the gate into the dark and ominous Dreamwald forest.  He soon slowed, for the run had left him out of breath. But he kept walking and walking.  Presently he noticed an old woman in black standing right in the middle of the path. He walked right up to her and said. “Excuse me old woman, but you are in my way, I would ask that you step aside right now.”

The old woman peered from beneath her hood and said “I’m waiting for you Albert. You left a wish at the wishing stone last night.  I’m here to make it right.”

“You have my wooden horse?” Albert asked, having left off the idea of getting past this women.

“I do, but you must promise to give me whatever I want. Promise right now.  “

He was left with no choice “I promise”

There was a boom and a crash and right next to Albert there was a gorgeous wooden horse. It left him breathless, and for the first time in his life, something left him speechless as well. It was more than he had hoped for.

“Is it all right?” asked the old crown.

“Oh yes” he replied “It is defiantly all right.

And then she began to cackle.  The noise left his ears ringing it was so loud. And them POOF, Albert was no longer in the woods. He was inside a hut, tied right to a spit, left spinning over an open fire. 

The old women continued to cackle as she pinched his left arm and licked her licks.

He screamed “Oh no!  This is not right!  In fairy tales the little child outsmarts the old witch. You have not left me a chance to even try!”

“You looked so tasty, I didn’t think it was right to play that silly old game. I decided to just put you right on the spit and roast you right away.”

Albert began to sob as the heat of the flames became more and more uncomfortable.  He was left with a feeling of utter despair.

Then, to his left, he heard the sound of sleigh bells, then he heard the stomping of many animals. Then one of the hut doors, the one on the left, opened up and a man in a big rid suit stepped inside and pointed at the old lady.

“Ismerelda!  You have left me no choice. Yes this boy is naughty, but you are worse.  You have no right to cook him, no matter how selfish and lazy he is!”  He lifted a staff in his right hand and brought it down with a thud on the ground. A blinding flash of light filled the hut and then snow began to fall right from the ceiling.  Big, wet flakes fell right on to the witch and quickly covered her, freezing her right where she stood.  The snow also fell right on the fire, till there were no flames left. 

Albert freed his right hand, then his right ankle, and then untied his… other arm and leg. 

“Thank you Santa! I thought I was left for dead!”

As the old man walked to the other door in the hut, the right door, he turned and said.  “Don’t thank me little boy. Thank your good parents and sisters. When you left them, you left them heartbroken and they asked for my help.  So I came right away and did what I could. Let this be a lesson to you.  You need to learn Wrong from Right!”

And with that, he left the hut, jumped into his sleigh, flew away, and left Albert with nothing but his thoughts.

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Configuring Laptop “Switchable” Graphics for ANSYS Applications


A lot of laptops these days come with “switchable” graphics.  The idea is that you have a lower capability but also lower power consuming ‘basic’ graphics device in addition to a higher performing but higher power demand graphics device.  By only using the higher performance graphics device when it’s needed, you can maximize the use time of a battery charge. 

A lot of the ANSYS graphics-intensive applications may need the higher end graphics device to display and run correctly.  In this article, we’ll focus on the AMD Firepro as the “higher end” graphics, with Intel HD graphics as the “lower end”.  We will show you how to switch to the AMD card to get around problems or errors in displaying ANSYS user interface windows.

The first step is to identify the small red dot graphics icon at the lower right in the task bar:


Figure 1 – AMD Catalyst Icon


Next, right click on the icon to bring up the AMD Catalyst Control Center, if you don’t see the switchable option as shown two images down.


Figure 2 – AMD Catalyst Control Center Right Click Menu Pick


Right click on the same icon again, if needed to select “Configure Switchable Graphics,” as shown here:


Figure 3 – Select “Configure Switchable Graphics” via Right Click on the Same Icon


In the resulting AMD Catalyst Control Center window, click on the Add Application button.


Figure 4 – AMD Catalyst Control Center Window

Next browse to the application that needs the higher end graphics capability.  This might take a little trial and error if you don’t know the exact application.  Here we select ANSYS CFD-Post and click Open.


Figure 5 – Selecting appropriate executable for switchable graphics

Finally, select the High Performance option from the dropdown for your chosen executable, then click the Apply button.


This should get your graphics working properly.  Again, the reason we have the two graphics choices is to allow us to better control power consumption based on the level of graphics that are needed per application.  Hopefully this article helps you to choose the proper graphics settings so that your ANSYS tools behave nicely on your laptop.

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Getting to know ANSYS – SIwave

This video is an introduction to ANSYS SIwave – an analysis tool for Integrated Circuits and PCBs

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In Memoriam: Dr. Mark Johnson


A picture of Mark in his office at PADT. The equations on the white board were not put there for the picture. This was taken after a meeting where he and members of his team solved a tough rotor dynamics problem for a customer.

It is with incredible sadness that we must inform you that our friend and co-owner of PADT, Mark Johnson, passed away on November 25th from complications due to melanoma. He was with his wife, resting comfortably when he left us. This is a huge loss to anyone that ever knew Mark.

He joined PADT in the early days with the goal of building the company’s product development capability.  His focus and the focus of his team was using engineering to make the world a better place.  They did this directly through their work in alternative energy and medical devices and indirectly by helping companies from a wide range of industries.  There are hydrogen powered cars and buses today humming down the street using pumps and blowers that were Mark’s creations. Doctors are using devices every day to treat patients that Mark helped to design and test.  He also participated in the Startup and Medical Device engineering community in Arizona, serving as a judge, mentor, and board member across multiple organizations.  And as a co-owner of PADT, he helped direct the company, contributing strongly to our culture and reputation in the community.

Before joining PADT, Mark had a similar impact at Garrett (AlliedSignal, Honeywell), The University of Arkansas, and Ballard.  Few people in our industry had such a strong understanding of engineering fundamentals and his ability to apply that basic knowledge to help customers across industries will be sorely missed.

Outside of work, Mark was a loving father and husband, who always took time to be with his wife and two children.  Those of you who knew him outside of work know how important they were to him, and he to them.  

Since his passing many people have asked how they can honor Mark or share their thoughts on him.  We are recommending that those who wish to honor him simply follow his example.  Look for the good in people, help others when you can, and always ask questions.  Mark was a master questioner and often answering those questions revealed more to the person he was asking the question of than anyone else.  He often began meetings with new customers and partners with a simple statement: “I want to warn you, I like to ask questions, lots of questions.”

In that this blog is mostly read by people in technology, the best way you can honor his memory is to carry on his mission of using technology to make the world a better place. Help a startup, develop a more efficient system, commercialize a new technology that improves the lives of the less fortunate, enhance patient care, or help to explore and understand our universe.  There are so many ways that those of us involved in engineering and science can make a huge difference, just as Mark did.

Please feel free to leave your thoughts about Mark in the comments below. If you would like to send a note or card to his family, please mail it to:

Mark Johnson Memorial
7755 S Research Dr, Suite 110
Tempe, AZ  85284

The family has asked that any donations be made to Heifer International or Hospice of the Valley.

Posted in News, PADT Medical, Product Development | Tagged , | 9 Comments

PADT Colorado Plays Catch on Google StreetView

padt-colorado-streetview-catch-tnTechnology has changed so much in our world that sometimes it is hard to get your head around it.  The fact that Google is driving and walking around the world taking a picture of streets everywhere is something easy to say, but had to comprehend. Everyone now has the chance of having their blurred face saved for posterity – if you are in the right place at the right time.

On my current visit to PADT’s Colorado office someone mentioned that Manoj and Stephen were caught on Google Street View outside our office. I figured they were snapped while running out the front door to leap into a car and speed off to do an impromptu demo or provide face-to-face technical support to a struggling customer.  something heroic and super hero like in a technical-guy sort of way.

So I went to Google maps and put in “PADT Colorado” and clicked on street view:
Looks like a nice summer day on main street in historic downtown Littleton. You can see the US, Colorado, and PADT flags on the balcony of our office.  I bet if I move down the street I’ll see them racing out the door.

Nope, I don’t see their cars either, maybe they are in the parking lot. Wait, that kind of looks like Manoj on the left side of the street in the blue shirt.  Let’s go one more pic down the road.

There they are, Manoj and Steve!  Being the engineers that they are, they of course recognized the Google StreetView car and Manoj is waiving at it. Hey, what is that… a football?  They weren’t rushing to solve a technical emergency, they were playing catch in the grass on a sunny bright day!  No computers, laptop bags, or pocket protectors. 

Much cooler thing to get caught doing on street view.  Bravo.

The next pictures shows Stephen saying hello to the world as well.  Awesome.

They both made PADT proud in their 1500 pixels of fame.

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ANSYS Workbench Installations and RedHat 6.6 – Error and Workaround

penguin_shWe were recently alerted by a customer that there is apparently a conflict with ANSYS installations if Red Hat Enterprise Linux 6.6 (RHEL 6.6) is installed. We have confirmed this here at PADT. This effects several versions of ANSYS, including 15.0.7, 14.5, and 14.0. The primary problem seems to be with meshing in the Mechanical or Meshing window.

The error encountered can be: “A software execution error occurred inside the mesher. The process suffered an unhandled exception or ran out of usable memory.” or “an inter-process communication error occurred while communicating with the MESHER module.”

The error message popup can look like this:


Note that the Platform Support page on the ANSYS website does not list RHEL 6.6 as supported. RHEL is only supported up through 6.5 for ANSYS 15.0. This is the link to that page on the ANSYS website:

That all being said, there is a workaround that should allow you to continue using ANSYS Workbench with RHEL 6.6 if you encounter the error. It involves renaming a directory in the installation path:

In this directory:


Rename the folder ‘X11’ to ‘Old-X11’

After that change, you should be able to successfully complete meshes, etc,. in ANSYS Workbench. Keep in mind that RHEL 6.6 is not officially supported by ANSYS, Inc. and their recommendation is always to stick with supported levels of operating systems. These are always listed in the ANSYS Help for the particular version you are running as well as at the link shown above.

Since the renamed directory is contained within the ANSYS installation files, it is believed that this will not affect anything else other than ANSYS. Use at your own risk, however. Should you encounter one of more of the errors listed above, we hope this article has provided useful information to keep your ANSYS installations up and running.

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From Piles to Power – My First PADT PC Build

Welcome to the PADT IT Department now build your own PC

[Editors Note: Ahmed has been here a lot longer than 2 weeks, but we have been keeping him busy so he is just now finding the time to publish this. ]

I have been working for PADT for a little over 2 weeks now. After taking the ceremonial office tour that left me with a fine white powder all over my shoes (it’s a PADT Inc special treat). I was taken to meet my team, David Mastel – My Boss for short, who is the IT commander & chief at PADT Inc. and Sam Goff – the all-knowing systems administrator.

I was shown to a cubicle that reminded me of the shady computer “recycling” outfits you’d see on a news report highlighting the vast amounts of abandoned hardware; except there were no CRT (tube) screens or little children working as slave labor.

Sacred Tradition

This tradition started with Sam, then Manny, and now it was my turn taking this rite of passage. As part of the PADT IT department, I am required by sacred tradition to build my own desktop with my bare hands – then I was handed a screwdriver.

My background is mixed and diverse but mostly has one thing in common. We usually depended on pre-built servers, systems and packages. Branded machines have an embedded promise of reliability, support and superiority over the custom built machines.

  1. What most people don’t know about branded machines is that they carry two pretty heavy tariffs.
  2. First, you are paying upfront for the support structure, development, R&D, supply chains that are required to pump out thousands of machines.
  3. Second, because these large companies are trying to maximize their margins, they will look for a proprietary cost effective configuration that will:
    1. Most probably fail or become obsolete as close as possible to the 3-year “expected” life-span of computers.
    2. Lock users into buying any subsequent upgrade or spare part from them.

Long Story short, the last time I fully built a desktop computer was back in college when a 2GB hard disk was a technological breakthrough that we could only imagine how many MP3’s we could store on it.

The Build

There were two computer cases on the ground, one resembled a 1990 Mercury Sable that was at most tolerable as a new car and the other looked more like 1990 BMW 325ci a little old but carries a heritage and potential to be great once again.

So with my obvious choice for a case I began to collect parts from the different bins and drawers and I was immediately shocked at how “organized” this room really was. So I picked up the following:

There are a few things that I would have chosen differently but were not available at the time of the build or were ridiculous for a work desktop would be:

  • Replaced 2 drives with SSD disks to hold OS and applications
  • Explored a more powerful Nvidia card (not really required but desired)

So after a couple of hours of fidgeting and checking manuals this is what the build looks like.

(The case above was the first prototype ANSYS Numerical Simulation workstation in 2010. It has a special place in David’s Heart)

Now to the Good STUFF! – Benchmarking the rebuilt CUBE prototype

ANSYS R15.0.7 FEA Benchmarks

Below are the results for the v15sp5 benchmark running distributed parallel on 4-Cores.

ANSYS R15.0.7 CFD Benchmarks

Below are the results for the aircraft_2m benchmark using parallel processing on 4-Cores.

This machine is a really cool sleeper computer that is more than capable at whatever I throw at it.

The only thing that worries me is that when Sam handed me the case to get started, David was trying –but failed- to hide a smile that makes me feel that there is something obviously wrong in my first build and I failed to catch it. I guess I will just wait and see.

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