Running Ansys Fluent on Ansys Cloud using a Journal File and a UDF

Cloud computing is becoming more and more popular with the recent changes in the work environment, and Ansys Cloud solution is no exception. While running a Fluent simulation on the Ansys Cloud is now a more familiar task among CFD users since its introduction around a year ago, there are still some cases that might be challenging and need more attention. One of these cases is performing a Fluent simulation using a UDF.

The first thing users might notice when launching an Ansys Cloud Fluent job through the ACT extension is that the UDF files won’t be uploaded, which is why they might see their cases are failing if they don’t pay extra attention. In order to avoid this issue, users must follow one of the options below.

The first and most commonly used method to launch a Fluent job with a UDF is via the CLI (Command Line Interface). With this method, the .c and all other files in the working directory will be uploaded to the Cloud. Then UDF will then be compiled on the Cloud.

Since the Cloud computers already have compilers installed, one doesn’t need to anything special. The local directory should have .c file, case file with UDF plugged-in, and a journal file. As a side note, Ansys Fluent 19.3 and higher supports expressions that can be used to define boundary conditions instead of UDF. Starting with Ansys Fluent 2020R2, the C compiler is built-in with the software. Please refer to the product documentation.

We highly recommend that the user should have the required compiler installed locally to compile, hook, and test the routine before submitting it to the cloud.

If you have not used CLI to submit a Fluent job to the clouds, please read the article below:

https://cloudforum.ansys.com/t/80njy9/how-to-running-fluent-on-cloud-using-a-journal-file-and-udf

In short, you have to open a command prompt (cmd.exe) and navigate to your working folder. This folder should contain all the Fluent input files needed for the run: journal file, case file, etc. Once you login using ansyscloudcli command, you are ready to submit your job on the cloud.

Below is a common example for the commands to run Fluent on the cloud:

ansyscloudcli runfluent -j fluent_via_journal --jou tjunction.jou –q Flexible_eastus_Standard_HC44rs_2020r2 -n 1 -m 36 -v 2020r2

Here is some description of these commands:

> AnsysCloudCLI runFluent -j <job name> [--jou <journal>] -q <queue>  [-n <num nodes>] [-m <max cores>] -v <solver version>
-j: job name
-q: name of the queue 
    (run: ansyscloudcli getQueues, to get a list of all queues. Queue name is case sensitive)
-i: name of the input file for the solver
--jou: journal to execute (if set, -i is not used)
-n: number of nodes
-m: (optional) max number of cores. Useful if you want to make a run with 4 cores on a computer with 16 cores
-v: target solver version

The second method is to compile the UDF locally and upload all files to a virtual desktop infrastructure (VDI) session. Then the compiled UDF can be used with Fluent through the VDI session. Note that the UDF can’t be compiled on a VDI session with versions 2020R2 and earlier.

Lastly, with 2021R1 Fluent has a built in Clang compiler which will allow you to compile a UDF in a VDI session. However, the Clang compiler still won’t allow you to submit a Fluent job with a UDF through the ACT.

Ansys Cloud VDI solution running on a local desktop via RDP

All Things Ansys 081: Meshing & UI updates in Ansys Fluent 2021 R1

 

Published on: February 8th, 2021
With: Eric Miller & Sina Ghods
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s Senior Simulation Support & Application Engineer and fluids expert Sina Ghods for a look at what’s new in this release.

For fluids simulation in this release, products can be designed faster than ever before, thanks to major physics and productivity enhancements that build upon the tool’s ​already powerful workflow and meshing capabilities.

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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Workflow & Meshing Updates in Ansys Fluent 2021 R1 – Webinar

From small to mid-sized companies to global organizations, companies of every size seek new ways for pioneering breakthrough innovations that are safer and more reliable to win the race to market.

Ansys 2021 R1 delivers significant improvements in simulation technology together with nearly unlimited computing power to help engineers across all industries reimagine product design and achieve product development goals that were previously thought impossible.

For fluids simulation in this release, products can be designed faster than ever before, thanks to major physics and productivity enhancements that build upon the tool’s ​already powerful workflow and meshing capabilities. Join PADT’s Senior Simulation Support & Application Engineer and fluids expert Sina Ghods for a look at what’s new in this release including: 

• Fluent User Interface Updates

      • Meshing Workflow Advancements

      • Combustion Applications

      • Turbomachinery Applications

      • Battery Modeling Applications

      • Multiphase and DPM Improvements

If this is your first time registering for one of our Bright Talk webinars, simply click the link and fill out the attached form. We promise that the information you provide will only be shared with those promoting the event (PADT).

You will only have to do this once! For all future webinars, you can simply click the link, add the reminder to your calendar and you’re good to go!

Meshing in the New Ansys Fluent Task-based Workflows

Working with a variety of users with different levels of CFD (Computational Fluid Dynamics) backgrounds, I have to admit that Fluent meshing used to be a challenging and confusing task for beginners and even intermediate users.

Ansys has addressed this challenge by redesigning the Fluent user interface to provide a task-based workflow for meshing that enables engineers to do more and solve more complex problems than ever before in less time. The new Fluent task-based workflow streamlines the user experience by providing a single window that offers only relevant choices and options and prompts the user with best practices that deliver better simulation results.

Best practices are embedded into the workflow in the form of defaults and messages to the user. This reduces the amount of training required to start using the software and makes it easier for occasional users to return to the software.

How to Mesh Watertight CFD Geometry in the New Ansys Fluent Task-based Workflow

In order to use this workflow, you need a relatively clean watertight solid and/or fluid regions that can be meshed by surface meshing and then volume filling (no wrapping required.) Geometry can consist of single or multiple bodies.

Going through the task-based workflow is straightforward. You are presented with several steps, like:

  • Surface mesh.
  • Describe geometry. (Fluid and/or solid)
  • Capping. (If you are creating an internal flow volume, then the capping tools in Fluent makes extraction easy)
  • Volume meshing. (If you wish to use the latest Mosaic meshing technology, select “Poly-hexcore”)
Mosaic Meshing Technology

Now, click on “Switch-to-Solution,” to bring the mesh into a familiar Fluent interface.

Fault-Tolerant Workflow for Ansys Fluent Meshing Wraps and Seals Leaks and Gaps

Sometimes CFD simulations contain dirty, non-watertight geometries. For instance, 3D scanned or manufacturing geometry files. These geometries may contain missing faces, gaps, holes, overlaps, and other issues. As a result, they require extensive cleanup before simulation.

To overcome this obstacle, Ansys offers a new Fluent meshing workflow that wraps dirty geometry without cleanup.

The workflow for non-watertight geometry offers distinct advantages over other meshing technologies such as:

Part management:

Users can perform CAD-level changes to any geometry or assembly, including dragging and dropping objects from the CAD model into the simulation model.

Leakages and overlaps:

The fault-tolerant workflow seals leakages caused by gaps and misalignments between solid bodies. This significantly reduces the manual efforts required to clean up geometry.

The fault-tolerant workflow can easily wrap leaky geometry

STL file input

The workflow can create fluid regions directly from STL files or scanned data. This eliminates the need to convert STL files into solid geometry for the biomedical, oil and gas, automotive and other industries.

Imported STL File

2020R2 updates:

There are a few important improvements both in Watertight meshing (WTM) and Fault-Tolerant meshing (FTM) workflows in the 2020R2 release.

FTM/WTM: Wild card selection in lists

The Meshing Workflows now have an option to use a persistent Wildcard string for selecting labels or zones. This is in addition to the Filter Text option previously available. The new Use WildCard option stores the wildcard string itself in recorded workflows instead of an explicit list of locations so that when they are played back with new geometries, the matching will be performed again and pick up any matching zones/labels that were not in the earlier geometry.

WTM: Support of Region-specific Sizing 

You can specify region-specific Max Size and Growth Rates during the Volume Meshing task.  If you enable Region-based Sizing, Fluent will compute default sizing specifications for each region.  These can then be adjusted as required for each region.

WTM: Start From Imported Surface Mesh

This is useful if you have an established surface-meshing workflow or if you already have a mesh generated (perhaps from another preprocessor or an existing Fluent case) and want to use that as a starting point for Fluent meshing. Once you import the surface mesh you have the option of using it as it is, or selectively adding additional Local Size controls and/or remeshing particular surfaces as needed.

FTM: Continuous prism layers for Poly and Poly-Hexcore for Fluids

For the Fault-Tolerant Meshing Workflow you can now create continuous prism layers without stair-stepping within poly and poly-hexcore fluid regions.  Note that this will apply in all zones of the region.

WTM: Support of Local Sizing on Labeled Edges

Once you have labeled the edges, you can select Edge Size in Add Local Sizing to prescribe a target size on the selected edge(s).

All Things Ansys 069: Fluent Updates in Ansys 2020 R2

 

Published on: August 10th, 2020
With: Eric Miller & Sina Ghods
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by Senior Application Engineer, Sina Ghods for a discussion on what’s new and their favorite features in the 2020 R2 update for Ansys Fluent.

Known for delivering the most accurate solutions in the industry without compromise, Ansys continues to provide cutting-edge advancements with each new release. In 2020 R2 users can learn about updates from pre-processing to new physics models and workflow improvements.

If you would like to learn more about this update, you can view Sina’s webinar on the topic here: https://www.brighttalk.com/webcast/15747/427082

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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Fluent Updates in Ansys 2020 R2 – Webinar

The industry-leading fluid simulation software Ansys Fluent is capable of predicting fluid flow, heat & mass transfer, chemical reactions and other related phenomena.

Known for delivering the most accurate solutions in the industry without compromise, Ansys continues to provide cutting-edge advancements with each new release. In 2020 R2 users can learn about updates from pre-processing to new physics models and workflow improvements.

Join PADT’s Senior Simulation Support & Application Engineer Sina Ghods for an in depth discussion on what is new and improved in this version of Ansys Fluent, covering topics such as:

– Meshing Workflows

– Battery Modeling

– Multi-phase & DPM Flow

– Solver Enhancements

– And Much More

Register Here

If this is your first time registering for one of our Bright Talk webinars, simply click the link and fill out the attached form. We promise that the information you provide will only be shared with those promoting the event (PADT).

You will only have to do this once! For all future webinars, you can simply click the link, add the reminder to your calendar and you’re good to go!

Fluent Updates in ANSYS 2020 R1 – Webinar

Computational fluid dynamics (CFD) can be challenging for a multitude of reasons, but not with ANSYS Fluent. Anyone can get great CFD simulation results with ANSYS solutions. Fluent software contains the broad, physical modeling capabilities needed to model flow, turbulence, heat transfer and reactions for industrial applications. These range from air flow over an aircraft wing to combustion in a furnace, from bubble columns to oil platforms, from blood flow to semiconductor manufacturing and from clean room design to wastewater treatment plants.

Fluent spans an expansive range, including special models, with capabilities to model in-cylinder combustion, aero-acoustics, turbomachinery and multiphase systems. The latest innovations and updates simplify and speed setup and meshing while adding even more accurate physical models. The outcome: great results, without compromise.

Join PADT’s Senior CFD & FEA Application Engineer, Sina Ghods, for a look at what’s new and improved in this latest version of ANSYS Fluent, including:

  • User Interface/Graphics
  • Meshing Workflows
  • Multi-phase Robustness
  • Solver Enhancements
  • And much more

Register Here

If this is your first time registering for one of our Bright Talk webinars, simply click the link and fill out the attached form. We promise that the information you provide will only be shared with those promoting the event (PADT).

You will only have to do this once! For all future webinars, you can simply click the link, add the reminder to your calendar and you’re good to go!

All Thing ANSYS 054: Talking CFD – Discussion on the Current State of Computational Fluid Dynamics with Robin Knowles

 

Published on: January 13th, 2020
With: Eric Miller & Robin Knowles
Description:  

In this episode we are excited to share an interview done with host and Co-Founder of PADT, Eric Miller and host of the Talking CFD podcast Robin Knowles, regarding the history of PADT’s use of simulation technology as a whole, and the current state of all things CFD.

If you would like to hear more of Robin’s interviews with various other CFD based companies both small and large, you can listen at https://www.cfdengine.com/podcast/.

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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Fluids Innovations in ANSYS 2019 R3 – Webinar

Products such as ANSYS Fluent, CFX, and Ensight work together in a constantly improving tool kit that is developed to provide ease of use improvements for engineers simulating fluid flows and the impact those flows have on physical models. 

Fluids simulation users will find that ANSYS 2019 R3 includes many enhancements that further simplify the user experience and broaden use to new applications. The new Fluent experience has been improved so you can enjoy more CFD in less time, with less training.

Join PADT’s Simulation Support and Application Engineer, Sina Ghods, for a look at what is new and improved for fluids simulation tools in ANSYS 2019 R3. This presentation includes updates regarding: 

  • Usability Enhancements
  • Watertight Geometry Workflow
  • TurboGrid & BladeEditor
  • Meshing Enhancements
  • And many more innovative capabilities

Register Here

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Fluids Updates in ANSYS 2019 R2 – Webinar

ANSYS CFD goes beyond qualitative results to deliver accurate quantitative predictions of fluid interactions and trade-offs. These insights reveal unexpected opportunities for your product — opportunities that even experienced engineering analysts can miss.

Products such as ANSYS Fluent, Polyflow, and CFX work together in a constantly improving tool kit that is developed to provide ease of use improvements for engineers simulating fluid flows and it’s impacts on physical models.

Join PADT’s Simulation Support and Application Engineer, Sina Ghods, for a look at what is new and improved for fluids-related tools in ANSYS 2019 R2. This presentation includes updates regarding:

A new fluent experience

Parallel Mosaic-enabled meshing

Discrete Phase Modeling

Creating high-quality meshes for complex models

Transient elasticity for fluid structure interaction

And much more

Register Here

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All Things ANSYS 034 – Celebrating 25 Years of ANSYS Simulation: Changes In The Last Quarter Century & Where The Future Will Take Us

 

Published on: April 8th, 2019
With: Eric Miller, Ted Harris, Tom Chadwick, Sina Ghods, & Alex Grishin
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s Ted Harris, Tom Chadwick, Sina Ghods, and Alex Grishin, for a round-table discussion on their experience and history with simulation, including what has changed since they started using it and what they’re most impressed and excited by, followed by some prediction and discussion on what the future may hold for the world of numerical simulation.

Thank you again for those of you who have made the past 25 years something to remember, and to those of you who have come to know PADT more recently, we look forward to what the next 25 will bring.

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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All Things ANSYS 030 – Updates Available in ANSYS Fluent 2019 R1

 

Published on: February 13th, 2019
With: Eric Miller, Tom Chadwick, & Sina Ghods
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by Sina Ghods, and Tom Chadwick from the Simulation Support Team for a discussion on their favorite updates available in the latest release of ANSYS Fluent so far, followed by an update on news and upcoming events pertaining to PADT and ANSYS Simulation.

Want to learn more about what to expect in ANSYS Fluent 2019 R1? Check out PADT’s webinar covering everything you need to know about the tool’s latest update.

Watch here: https://bit.ly/2SJBFC4

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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Gone Skiing: Aerodynamics – Does It Matter Which Way Your Skis Are Pointing On Your Roof Rack?

I was on the gondola up at Keystone for night-skiing a week ago, after a long day at Beaver Creek, because the last thing I am going to do at 3:00 pm is try to make it back to Denver, as everyone knows it’s hardly more than a parking lot at that point. As it gets later, there’s nothing like a solo gondola ride, however, a solo ride would stop this story right about now.

On the gondola, I overheard a conversation where one gentleman was discussing how he was unable to open the hatch of his vehicle when his skis are in his roof rack. That’s fair, I know older WRX wagons with the spoiler would not be able to open with skis on the roof no matter what, so I figured that was the case. It turns out, that was NOT the case. The reason his hatch would not open was that he orients the skis with the tails forward because it is ‘more aerodynamic’ that way… I was skeptical, but held my tongue, knowing that I had the tools at my disposal to investigate!

I decided to make a model that would allow me to simulate various conditions to get to the bottom of this. My initial hypothesis is that the addition of the ski rack and crossbars is what has the largest effect on aerodynamics, and orientation of the skis probably has a negligible effect after that. As a side note, I am solely concerned with aerodynamics in this case, and am not worrying about the amount of the ski’s base material that is exposed for a given orientation. I am of the mindset that tree trunks and hidden rocks on the mountain are more of a danger to your bases than small rocks on the highway anyway. If you are waiting to comment, “Just get a roof box!”, I understand as I own both a box and a rack at this point, and they both have their advantages, and I will not be exploring the aerodynamics of a box…

…yet…

I was able to start by finding some faceted geometry of a Subaru Forester online (I’m from Colorado, can you tell?) and was able to import that into ANSYS Spaceclaim. Once in Spaceclaim, I was able to edit the faceted geometry to get nice exterior panel surfaces, which I then combined to get a single clean faceted exterior for the car.


Faceted Forester Geometry (Equipped with factory side rails)

After that, I used Spaceclaim to generate the remainder of the rack and skis, including crossbars, a ski rack, and a pair of skis (Complete with the most detailed bindings you have ever seen!). I made a combined part of the crossbars, rack, and skis for each one of my orientations, as this allows me to report the forces on each combined part during the simulation. Check now retainedfirefighter to more details .


Added CAD geometry for the crossbars, ski rack, and a pair of skis

For the simulation, I used ANSYS Discovery Live, the newest tool from ANSYS that allows for instant and interactive design exploration. This tool lets me actively add my CAD geometry and shows results in realtime. I was able to start with just the car and then add and swap my ski/rack geometry with simple button clicks. With traditional simulation tools, I would have needed to create a mesh for each one of these cases, analyze them one at a time, and the post-process and compare results after the fact. After launching Discover Live, it’s as easy as selecting the type on analysis I want to run.

The various types of solutions that can be done in ANSYS Discovery Live. For the purpose of this blog, I am using ‘Wind Tunnel’

Once I have selected ‘Wind Tunnel’ for my solution, I can select my geometry, and then am prompted for the direction of flow, as well as selecting the ‘floor’ of my domain. Once that is done, results show up on the screen instantly. I only needed to modify the flow velocity to ~65 mph. I am most interested in the force on the faces of the combined crossbars, rack, and skis in each orientation, so I created Calculations for each one, which is done by simply selecting the part and using the popup toolbar to create the graph.

Popup toolbar allows for the quick creation of solution calculations

I was already off and running. I ran each one of the cases until the force plot had become steady.

Car Only
Skis Tips Forward Orientation

Skis Tails Forward Orientation

Seeing that the force results for the Tips Forward vs. Tails Forward cases were very similar, I decided I should also run a ‘Bases Up’ Orientation, even though I STRONGLY advise against this, as UV wrecks the base material of your skis/snowboard.

Ski Bases Up and Tips Forward Orientation

In addition to the contour plot shown in the images above, you can also use emitters to show streamlines and particle flow, which also give some pretty neat visualizations.

Streamlines shown on the Tips Forward orientation

Particle Emitter shown on the Tips Forward orientation

The graph plots show values for the Total Y Force for Tips Foward, Tails Forward, and Bases Up orientations to be 37.7 N, 39.1 N, and 37.1 N, respectively. Using Discovery Live, I was able to quickly run all 3 of these simulations, showing that there is not a major difference in the forces on the ski rack between the three orientations. So, put the skis on the roof in the direction that makes life easiest for you, and keep those bad boys paired to protect your bases from the sun, because splitting them isn’t going to help with aerodynamics anyway!

Next steps would be taking a specific case and running in 2D, then 3D, in ANSYS Fluent.

Fluent Updates in ANSYS 2019 R1 – Webinar

Computational Fluid Dynamics (CFD) is a tool with amazing flexibility, accuracy and breadth of application. Serious CFD, the kind that provides insights to help you optimize your designs, could be out of reach unless you choose your software carefully.

Experienced engineers need to go further and faster with well-validated CFD results across a wide range of applications, and with ANSYS Fluent users are to do just that; delivering reliable and accurate results.

Join Padt’s CFD Team Lead Engineer, Clinton Smith for a look at what new capabilities are available for the latest version of Fluent, in ANSYS 2019 R1.

This presentation will be focused on eight main sections, including:

  • User Interface
  • Preprocessing
  • Workflow Enhancements
  • Solver Enhancements
  • Transient Enhancements
  • Applications
  • Physics
  • Optimization

Learn how Fluent is the most effective tool for simulating fluid flow, various types of erosion, and much more.

Register Here

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Meshing Enhancements in ANSYS 19.2 – Webinar

Don’t miss this informative presentation – Secure your spot today!

If this is your first time registering for one of our Bright Talk webinars, simply click the link and fill out the attached form. We promise that the information you provide will only be shared with those promoting the event (PADT).

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