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.


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

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!

Introducing ANSYS 2019 R1

PADT is excited to announce the release of ANSYS 2019 R1, the first group of updates for the suite of ANSYS simulation software this year. The release features updates for a wide variety of applications, including simulation for fluids, structures, electronics, 3D design, and much more.

We will be hosting a series of live webinars over the course of 2019 that will allow you to learn about what’s new in this release, from PADT’s team of expert support engineers.

Take a look at the following upcoming product update webinars for 2019 R1 and register by clicking the links below.

There is more to come, so stay tuned


Fluent Updates in ANSYS 2019 R1
Wednesday, February 13th – 11:00 am – 12:00 pm MST AZ

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 able 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.

Register Here


Mechanical Updates in ANSYS 2019 R1
Wednesday, March 13th – 11:00 am – 12:00 pm MST AZ

From designers and occasional users looking for quick, easy, and accurate results, to experts looking to model complex materials, large assemblies, and nonlinear behavior, ANSYS Mechanical enables engineers of all levels to get answers fast and with confidence. With applications for everything form strength analysis to topology optimization, it’s no wonder this comprehensive suite of tools continues to serve as the flagship mechanical engineering software solution.

Join PADT’s Simulation Support Manager, Ted Harris for a look at what new capabilities are available for ANSYS Mechanical, in the latest version; 2019 R1.

Register Here


High Frequency Electromagnetics Updates in ANSYS 2019 R1
Wednesday, April 10th – 11:00 am – 12:00 pm MST AZ

In today’s world of high performance electronics and advanced electrification systems, the effects of electromagnetic fields on circuits and systems cannot be ignored. ANSYS software can uniquely simulate electromagnetic performance across component, circuit and system design, evaluating temperature, vibration and other critical mechanical effects.

Join PADT’s Electrical Engineer, Michael Griesi for a look at what new capabilities are available with regards to High Frequency Electromagnetics, in the latest version of ANSYS; 2019 R1

Register Here


Discovery Updates in ANSYS 2019 R1
Wednesday, May 8th – 11:00 am – 12:00 pm MST AZ

The ANSYS 3D Design family of products enables CAD modeling and simulation for all design engineers. Since the demands on today’s design engineer to build optimized, lighter and smarter products are greater than ever, using the appropriate design tools is more important than ever.

Join PADT’s Simulation Support Manager, Ted Harris for a look at what exciting new features are available for design engineers in both Discovery Live and AIM, in ANSYS 2019 R1.

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 Things ANSYS 027 – 2018 Wrap-up – Our Favorite ANSYS Features From This Year

 

Published on: December 17th, 2018
With: Eric Miller, Tom Chadwick, Joe Woodward, & Ahmed Fayad
Description:  

 

In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s Simulation Support Team, including Tom Chadwick, Joe Woodward, and Ahmed Fayad for a round-table discussion of their favorite ANSYS features released in 2018, along with news regarding the PADT and ANSYS worlds.

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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@ANSYS #ANSYS

All Things ANSYS 025 – Elevating Post Processing with ANSYS Ensight

 

Published on: November 19th, 2018
With: Eric Miller & Clinton Smith
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s CFD Team Lead Engineer and PhD, Clinton Smith to discuss what makes ANSYS Ensight so special, including the boost it gives to both post processing speed and visualization quality by implementing ANSYS Ensight. All that, followed by an update on news and events in the respective worlds of ANSYS and PADT.

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 023 – Exploring the Latest & Greatest in ANSYS 19.2

 

Published on: October 22nd, 2018
With: Eric Miller, Joe Woodward, Ted Harris, & Tom Chadwick
Description:  

In this episode the technical support staff at PADT returns to join your host and Co-Founder of PADT, Eric Miller for a discussion on their favorite additions in ANSYS 19.2. This conversation includes PADT’s Specialist Mechanical Engineer Joe Woodward, Simulation Support Manager Ted Harris, & Senior CFD Engineer Tom Chadwick, and is followed by an update on news and events in the respective worlds of ANSYS and PADT.

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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@ANSYS #ANSYS

ANSYS Discovery Live – Fluid Flows Webinar Recording & FAQ

Below you can find some of the most frequently asked questions from this webinar, along with our answers.

Q: What computer and license type are you actually using for running the simulation? Ram, cores, CPU, etc.

A: 16 GB RAM Intel i7, NVIDIA Quadro K1100M

Q: Is the solver running a transient solution in the background while you are post processing and haven’t paused it, or is it marching towards better convergence of a steady state solution?

A: The solver is running a transient solution the entire time. The only time it is not doing this is if I pause the simulation.

Q: Does this require 3D models to be built within Discovery Live, or it can import outside 3D models (Solidworks etc) and still allows the user to add/modify geometry objects on the fly within Discovery Live?

A: Yes, you can import any CAD native format or neutral format in Discovery Live. You can also create Geometry from scratch in Discovery Live using the SpaceClaim tools.

Q: It looks like when you change the “speed – fidelity” setting, the solver resets; while when you change other settings (like domain geometry), the solution continues from last step. What’s being changed when you change the “speed-fidelity” setting?

A: When you change the Speed-Fidelity setting, the computational grid of the domain is coarsened or refined. It is also re-partitioned/parallelized on the GPU cores.

Q: Are there predictive features of simulation, obtaining design suggestions from the end results? Are there inputs for end results to accomplish reverse engineering?

A: Yes, in a sense. Because Discovery Live provides literally “real-time” feedback on design changes, you have design suggestions based on the end results. For reverse engineering in Discovery Live: there are not inputs for end results, but the part you’d like to reverse engineer can be imported (or created) in Discovery Live, and then analyzed in the range of operating conditions to understand it’s performance.

Q: Do you have any control of the mesh? How boundary/layer effects can be checked?

A: Control of the mesh available via the Speed-Fidelity slider bar. Boundary layer effects could be checked using surface integrals of force, but again recall that if you’re trying to finely resolve details such as boundary layer physics, you may need to consider the next level of accuracy which would be Discovery AIM or Fluent.

If you have any other questions, feel free to contact us at sales@padtinc.com or contact PADT’s CFD Team Lead Application Engineer Clinton Smith at clinton.smith@padtinc.com.

All Things ANSYS 014 – Fluid Flows with ANSYS Discovery Live & the ANSYS Startup Program

 

Published on: February 26, 2018
With: Joe Woodword, Tom Chadwick, Ted Harris, Clinton Smith, Eric Miller
Description: In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s Joe Woodword, Tom Chadwick, Clinton Smith, and Ted Harris, for a discussion on the internal and external fluid flow capabilities available in ANSYS Discovery Live. This episode also features a very special interview with ANSYS’ own Paul Lethbridge, Senior Manager of the Academic and Startup Programs, recorded live at Phoenix Startup Week.
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Explore the fluid flow capabilities available in Discovery Live – Webinar

This free webinar will cover:

  • How to gain early insights into trends of pressure drag, drop & drift
  • The capability of gathering qualitative information for flow dispersion & thermal mixing
  • Exploration of recirculation zones and experimentation with changing flow direction
  • And so much more!

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

Can’t make it? Register anyway, as a recording will be made available to be watched on-demand.

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 Things ANSYS 012 – Live From New Mexico: A Look at What’s New in ANSYS 19

 

Published on: January 30, 2018
With: David Mastel, Joe Woodword, Manoj Mahendran, Matt Sutton, Michael Griesi, Tom Chadwick, Ted Harris, Eric Miller
Description: In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s David Mastel, Joe Woodword, Manoj Mahendran, Matt Sutton, Michael Griesi, Tom Chadwick, and Ted Harris, for a discussion on what is new and improved in the recently released ANSYS 19.
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All Things ANSYS Episode 008 – Looking at Explicit Dynamics and CFD tools in ANSYS pt. 1

Published on: November 6, 2017
With: Tom Chadwick, Joe Woodward, Jim Peters, Ahmed Fayad, Eric Miller
Description: In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s Senior CFD Engineer Tom Chadwick, Senior Mechanical Engineer Joe Woodward, Senior Staff Technologist Jim Peters, and IT Operations and Support Engineer Ahmed Fayad for the first part of an in depth look at Explicit Dynamics in ANSYS along with a review of the various CFD tools available in the ANSYS family of products.
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All Things ANSYS Episode 005 – Getting to know convergence better and hidden gems in the ANSYS product family

Published on: September 25, 2017
With: Tom Chadwick, Ted Harris, Eric Miller
Description: In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s Senior CFD Engineer Tom Chadwick,  and Simulation Support Manager Ted Harris for a discussion on convergence with both FEA and CFD solutions, as well as a look at some of their favorite hidden gems in the ANSYS tools set. Learn about some beneficial ANSYS capabiliites you may not be aware of!
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All Things ANSYS Episode 004 – Fun fluid additions in ANSYS 18.2 and the disruptive nature of Discovery Live

Published on: September 11, 2017
With: Jim Peters, Tom Chadwick, Ted Harris, Eric Miller
Description: In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s Senior CFD Engineer Tom Chadwick, Senior Staff Technologist Jim Peters, and Simulation Support Manager Ted Harris for a look at the CFD updates available within ANSYS 18.2, along with a discussion on why they love the new disruptive simulation tool from ANSYS; Discovery Live.
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Superior CFD Requires Superior Software – ANSYS Fluent 18.2 Webinar

As Computational Fluid Dynamics (CFD) remains one of the most flexible and accurate tools for developing solutions involving fluid flows in a variety of industries, it is important of engineers to stay up to date on the software that makes it all possible: ANSYS.

Thanks to the latest version ANSYS Fluent, engineers now more than ever, can generate unexpected insights and additional value, helping to greatly improve the effectiveness of their product development process.

Join PADT’s CFD Team Lead Engineer, Clinton Smith, for a live webinar, covering the various improvements and enhancements made to the Fluent tool in ANSYS 18.2.

By attending this webinar, you will learn how Fluent 18.2 can help users to:

  • Define a scalar transport equations to improve results for chemical species
  • Visualize injection position and orentation during model setup
  • Accurately predict cavitation in high pressure devices with non-condensable gases
  • And much more!

Don’t miss your chance to attend this upcoming event,

click below to 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).

 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!

Getting to Know PADT: Simulation Services

This is the fourth installment in our review of all the different products and services PADT offers our customers. As we add more, they will be available here.  As always, if you have any questions don’t hesitate to reach out to info@padtinc.com or give us a call at 1-800-293-PADT.

The A in PADT actually stands for Analysis.  Back in 1994 when the company was started, computer modeling for mechanical engineering was called Analysis. It was such an important part of what we wanted to achieve that we put it in the name.  Unfortunately, Analysis was a bit to generic so the industry switched to Numerical Simulation, or simply simulation. In the 23 years since we started, analysis… sorry, simulation, has been not just a foundation for what PADT does for our customers, it has become a defacto tool in product development.  Through it all there has been a dedicated group here that is focused on providing the best simulation as a service to customers around the world.

Driving Designs with Simulation

Many companies know about PADT with regards to simulation because we are an ANSYS Elite Channel Partner – selling and supporting the entire suite of ANSYS simulation tools in the Southwestern US. The success of simulation in the design and development of physical products is a direct result of the fact that these fantastic tools from ANSYS can be used to drive the design of products.  This can be done in-house by companies designing the products, or outsourced to experts. And that is where PADT has come in for hundreds of customers around the world.  The expertise we use to support and train on ANSYS products derives directly from our real world experience providing CFD, structural, thermal, electromagnetic, and multiphysics simulations to help those customers drive their product development.

For those not familiar with simulation, or who only use the basic tools embedded in CAD software as a quick check, understanding why it is so important hinges on understand what it really is. Numerical Simulation is a methodology where a physical product is converted into a computer model that represents its physical behavior.  This behavior can be many different physics: stresses, vibration, fluid flow, temperature flow, high frequency electromagnetic radiation, sloshing of liquids, deformation during impact, piezoelectric response, heating from static electromagnetic waves, cooling from air flow. The list goes on and on. Pretty much anything you studied in physics can be modeled using a numerical simulation.

The process of doing the simulation consists of taking the physical object and breaking it into discrete chunks, often very small relative to the size of the object, so that equations can easily be written for each chunk that describes the physical behavior of that chunk relative to the chunks around it.  Imagine writing equations for the fluid flow in a complicated valve housing, very hard to do. But if you break it up into about one million small polyhedrons, you can write an equation for flow in and out of each polyhedron. These equations are then assembled into a giant matrix and solved using linear algebra.  That is why we need such large computers.  We mostly use the world’s leading software for this, from ANSYS, Inc.

More than Building and Running Models

Knowing how to build and run finite element and CFD models is key to providing simulation as a service. PADT’s team averages over 18 years of experience and few people come close to their knowledge on geometry preparation, meshing, setting up loads and boundary conditions, leveraging the advantages of each solver, and post processing. That is a good starting point. But what really sets PADT apart is the understanding of how the simulation fits into product development, and how the information gathered from simulation can and should be used.  Instead of providing a number or a plot, PADT’s experienced engineers deliver insight into the behavior of the products being simulated.

How each project is conducted is also something that customers keep coming back for.  Nothing is ever “thrown over the wall” our passed through a “black box.” From quote through delivery of final report, PADT’s engineers work closely with the customer’s engineers to understand requirements, get to the heart of what the customer is looking for, and deliver useful and actionable information.  And if you have your own in-house simulation team, we will work closely with them to help them understand what we did so they can add it to their capabilities. In fact, one of the most popular simulation services offered by PADT is automation of the simulation process with software tools written on top of ANSYS products.  This is a fantastic way to leverage PADT’s experience and knowledge to make your engineers more efficient and capable.

Unparalleled Breadth and Depth

Based on feedback from our customers, the other area where PADT really stands out is in the incredible breadth and depth of capability offered.  Whereas most service providers specialize in one type of simulation or a single industry, more than twenty years of delivering high-end simulation to evaluate hundreds of products has given PADT’s team a unique and special level of understanding and expertise. From fluid flow in aerospace cooling systems to electromagnetics for an antenna in a smart toy, a strong theoretical understanding is combined with knowledge about the software tools to apply the right approach to each unique problem.

No where is this breadth and depth exemplified than with PADT’s relationship with ANSYS, Inc. Since the company was founded, PADT engineers have worked closely with ANSYS development and product management to understand these powerful tools better and to offer their advice on how to make them better.  And each time ANSYS, Inc. develops or acquires a new capability, that same team steps up and digs deep into the functionality that has been added. And when necessary, adding new engineers to the team to offer our customers the same expert access to these new tools.

 

The best way to understand why hundreds of companies, many of them large corporations that are leaders in their industry, come to PADT from around the world for their simulation services needs is to talk to us about your simulation services needs. Regardless of the industry or the physics, our team is ready to help you drive your product development with simulation. Contact us now to start the discussion.