{"id":39681,"date":"2022-10-11T11:05:25","date_gmt":"2022-10-11T18:05:25","guid":{"rendered":"https:\/\/www.padtinc.com\/?p=39681"},"modified":"2023-02-06T17:43:50","modified_gmt":"2023-02-07T00:43:50","slug":"ski-rack-aerodynamics-2-box","status":"publish","type":"post","link":"https:\/\/www.padtinc.com\/2022\/10\/11\/ski-rack-aerodynamics-2-box\/","title":{"rendered":"Optimal Ski Rack Aerodynamics Pt 2: “What about a box?”"},"content":{"rendered":"\n

The last few years have been different, to say the least. Regrettably, I haven\u2019t skied at all for the past two seasons, and my gear has just been gathering dust. However, a confluence of events has me both very excited for this ski season and also revisiting my blog post from nearly 4 years ago<\/a>. I\u2019ll start with a bit, or more than a bit, of backstory.<\/p>\n\n\n\n

Why I Care About Ski Rack Aerodynamics with a Box<\/h2>\n\n\n\n

I have helped Atomic at Colorado-area Labor Day ski sales since around 2008, only missing 2020 and 2021 dues to in-person events not occurring. As I was about to reach out to see what help may be needed this year, I received the text, \u201cYo dude, long time! Labor Day is happening\u2026.do you want to earn some Bents the hard way??\u201d The stoke for the season officially started to build. Even though Labor Day sales have changed drastically from good old days of SNIAGRAB at the Sports Castle in downtown Denver, they are always a blast.<\/p>\n\n\n\n

It was great to be back and chatting with people about the season to come and the \u2018need\u2019 for the new 120mm underfoot Atomic Bent Chetler with fresh graphics designed as always by Atomic athlete Chris Benchetler<\/a>. With the ski pass paid for and fresh gear ready to be mounted up, I really started to get excited for the season. No preparation for a ski season is complete without a key ingredient\u2026 a ski movie premiere.<\/p>\n\n\n\n

Not long after Labor Day sales had wrapped, I got another message, \u201cYo dude, just circling up to confirm if you can work the TGR events at the Oriental Theater?\u201d This was a surprise, and rightfully so because the message was not actually intended for me, but it turns out help was needed, and I\u2019m always happy to help out. The film this year from Teton Gravity Research is called Magic Hour<\/a> and was a really fun production with a mix of skiing, snowboarding, and clearly some time for a couple of athletes in a makeup chair. Anyway, I promise I\u2019m getting to the point!<\/p>\n\n\n

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\"Ski <\/picture>
The Oriental Theater filling up for the Friday showings of Teton Gravity’s Magic Hour <\/figcaption><\/figure><\/div>\n\n\n

With the Atomic Star banner deployed and a setup of 100mm, 110mm, and 120mm models of the Bent on display, Atomic athlete Sage Cattabriga-Alosa<\/a> was ready for autographs and some giveaways. While chatting with Sage, it turns out we have wildly different careers (who would have guessed?!) and I know from experience that when \u201cComputational Fluid Dynamics\u201d comes up in conversation outside of meetings at PADT, most people just stare back at me. <\/p>\n\n\n\n

However, I recalled part one of this blog and was able to pull it up on my phone and show what I had previously done, which was a perfect connection from the engineering world to a ski movie premiere. One of Sage\u2019s first questions was, \u201cWhat about a box?\u201d Immediately the wheels start turning in my mind of more analyses while Sage and I chat back and forth on what we think might be better or worse. A box is much larger but has a smoother form factor than a rack and skis. Would that make it better aerodynamically? This article started writing itself.<\/p>\n\n\n

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\"Ski <\/picture>
Sage Cattabriga-Alosa and I getting ready for the show.<\/figcaption><\/figure><\/div>\n\n\n

Use CFD to Look at Ski Rack Aerodynamics<\/h2>\n\n\n\n

With this backstory complete, I found myself at the computer finding all my old models and, luckily, finding quite a detailed CAD of a roof box on GrabCad<\/a>. A few minutes later, I had all my versions of CAD for a comparative analysis. This time I\u2019m using the Ansys Fluent Fault-Tolerant Workflow for meshing and Ansys Fluent for my analysis. The Fault-Tolerant Workflow lets me start with my old faceted vehicle and Ansys SpaceClaim-designed rack and ski configurations and create an external flow domain directly in the meshing workflow. The skis are designed to mimic the Atomic Backland 117 from a few years ago, with a good amount of tip-rocker and not much in the tails. All analyses use a flow velocity of 65mph.<\/p>\n\n\n\n

The cases I have at the start are:<\/p>\n\n\n\n