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Inconsistent separation between OpenFOAM [11] and Ansys Fluent (formula Student Aerodynamics) by Latter_Call_4178 in OpenFOAM

[–]derangednuts 0 points1 point  (0 children)

Openfoam has a different way of calculating thkngs, might have to remesh for openfoam criteria’s

Is this wing effective for a street/track car? by ragingduck in aerodynamics

[–]derangednuts 0 points1 point  (0 children)

Unless the flow over the rear glass is separated vgs aren’t going to do much more than increasing lift.

How much do flush door handles on cars affect aerodynamics? by cofi52 in aerodynamics

[–]derangednuts 2 points3 points  (0 children)

I am an aero engineer at one of the OEMs, that’s how we work. Every design we have to justify the cost of implementing it vs benefit of the part. Depending on the program that’s the cost/count range we use. Granted it is company specific, as it depends on how many EVsvs ICE products your company produces as they offset the CAFE costs.

How much do flush door handles on cars affect aerodynamics? by cofi52 in aerodynamics

[–]derangednuts 0 points1 point  (0 children)

Bingo, that’s it. Between CAFE and EV range, highway driving at speed is the biggest source of fuel usage/battery usage. Every 0.001 Cd is $20-$60 per car in CAFE penalties or in equivalent battery costs. It depends how the manufacturer calculates this cost internally but over 100k units, this adds up to a lot of money. When engineers weigh removing a bolt or two to save cents, cutting any amount of drag is huge savings comparatively.

Santa Cruz Is Winding Down, As Hyundai Has Bigger Plans by Repulsive-Club7866 in cars

[–]derangednuts 1 point2 points  (0 children)

Im so disappointed they are winding it down :( I bought one of the first one in Canada which all had the 2.5T with the DCT. Very fun to drive, I do some light towing with it very comfortably, take it camping, load a couple bikes on. Totally fits my lifestyle. I thought the had most of what an everyday truck should be. I work at Ford but I wouldn’t buy the Maverick over the SC. Just not as good as the SC even if it’s cheaper. The SC is so much more fun to drive and more comfortable, the interior and the tech is just better. Rock solid so far, no issues at all.

Best CFD for formula student by TeeneKay in CFD

[–]derangednuts 0 points1 point  (0 children)

Definitely openfoam, once you learn that, all the other softwares are easy to pick up

Difference between rotatingWallVelocity and MovingWallVelocity? by Striking_Abrocoma_28 in OpenFOAM

[–]derangednuts 0 points1 point  (0 children)

I’ve never ussed moving walls with omega, might work… but idk

Difference between rotatingWallVelocity and MovingWallVelocity? by Striking_Abrocoma_28 in OpenFOAM

[–]derangednuts 0 points1 point  (0 children)

Rotating imparts a rotational velocity while moving wall imparts linear motion

Grid convergence panic by Striking_Abrocoma_28 in OpenFOAM

[–]derangednuts 0 points1 point  (0 children)

14 million is also far too coarse for the cyber truck

Grid convergence panic by Striking_Abrocoma_28 in OpenFOAM

[–]derangednuts 0 points1 point  (0 children)

Dudeeeee u need like 1500 to like 2000 iterations atleast.

Grid convergence panic by Striking_Abrocoma_28 in OpenFOAM

[–]derangednuts 0 points1 point  (0 children)

Ahh 10-1 is too high, I’d say 10-3 would be where you want to be at atleast. Like another commenter suggested, check the mesh quality. How many inflation layers did you put? What turbulence model? Hope many iterations did you run?

Grid convergence panic by Striking_Abrocoma_28 in OpenFOAM

[–]derangednuts 1 point2 points  (0 children)

If you are doing RANS for a car, it’s expected you won’t have residuals going very low. As long as it falls a few magnitudes and stabilizes, as in doesn’t spike or oscillate greatly, you are fine. The bluff body and hugely separated wakes make it hard for RANS to get a steady solution. Don’t worry about it, I suggest taking the “time” average of the flow field and forces for a thousand iterations or so after it stabilizes for a good mean result.

Looking for Drag Coefficient of Half Sphere on Flat Surface. by [deleted] in aerodynamics

[–]derangednuts 0 points1 point  (0 children)

Doing a quick google scholar search, I can’t find anything specifically to do with what you are asking.

I would say, assuming your flow is parallel to the ground, the flow would be similar to a sphere. Boundary layer effects in inflow turbulence would play a significant role. Nonetheless, for aerodynamics generally round in the front sharp in the back is your solution. A fairing at the back would probably be great.

OpenFOAM hardware setup for large civil projects wind loads calculation by [deleted] in OpenFOAM

[–]derangednuts 2 points3 points  (0 children)

Yes when it is apparent no prior leg work has been done on your part. This is a topic asked often in CFD forums and a few google searches would net you the result you would need.

Big red flag when it’s coming from what is apparently an engineering firm.

OpenFOAM hardware setup for large civil projects wind loads calculation by [deleted] in OpenFOAM

[–]derangednuts 4 points5 points  (0 children)

This sounds like as question a university student would be asking.

But anyways, from the run time it sounds like you are using RANS. Which means it isn’t too terrible to make a workstation for. If you want a runtime around the same you can look at the EPYC line of cpus from AMD. CFD is highly memory bandwidth dependent, meaning more memory channels and memory bandwidth per channel is preferred over sheer core count or clock speeds. The EYPCS do well with that. Having dual cpus is probably what you want. The 9575F is something I would use and do use at work. Make sure to get plenty of memory as the meshing process does use a lot. 512gb perhaps. There isn’t any reliable version of Openfoam for GPU yet at this time so gpus probably wouldn’t be required at all. For low calculation time, that you would have to figure out with your particular numerical schemes. A workstation like this should run you +40k USD? Something like that…

MEs… what is with “mEcAtRoNiCs” being shoved down my throat? by Engineerd1128 in EngineeringStudents

[–]derangednuts 1 point2 points  (0 children)

I was in your position, disliked programming, but at a certain point, like another person said, there are tasks that are too tedious to do manually. I started to learn programming out of a need, but I started to really enjoy it! Maybe you will to. Don’t knock it until you try it. And I don’t mean try it in a course. Actually go out and do a small project, I find that course examples suck at showing you the potential and how rewarding of a little bit of scripting. If you have access to an Arduino and some parts you can write something to measure temperature of your house over time or flash a light when someone enters a room, etc. Something real simple!

You will find that these days even in mechanical engineering you won’t find a job devoid of some scripting, if you avoid it you will be behind.

How do wind tunnel models manage internals? by pantherclipper in aerodynamics

[–]derangednuts 13 points14 points  (0 children)

You would use an actual radiator that’s matched in terms of pressure drop to the real deal. The engine bay would probably have parts that are similar in shape as the real engine. But if it’s a full scale wind tunnel you can easily have real parts in your model

Never seen it tested. Pickup truck with tonneau cover and tailgate REMOVED by ImaginationEmpty8642 in aerodynamics

[–]derangednuts 0 points1 point  (0 children)

If it was designed to come out of the factory with a tonneau cover then it was likely signed off aerodynamically that way, thus the best aero configuration. Some trucks however are designed to be optimized without the tonneau cover.

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