CFD - Computational Fluid Dynamics, Motorsport, Formula 1

Here are our CFD links and discussions about aerodynamics, suspension, driver safety and tyres. Please stick to F1 on this forum.
Wayne Kerr
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Joined: Tue Dec 20, 2016 5:19 am

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula 1

Post by Wayne Kerr » Tue Dec 20, 2016 5:27 am

timhuang77 wrote::D Hi all,

I'm on an FSAE team trying to start Aero simulations for our car this year. I run Star-CCM+ v11 and are getting more and more familiar with CFD analysis. My question being: Where is the line drawn between 2D and 3D simulations? I understand that 3D is better at simulating viscous effects and estimating downforce and drag numbers. Currently, most of the vehicle simulations are done in 3D and ideally some would be done in 2D (as it is magnitudes faster computationally speaking). Our airfoil selection is done in 2D, but I would like to do more to speed up and simplify the process. Thanks
Have you watched the tutorial on steve portal for fsae? I'd start there if you haven't.

For your application, I probably wouldn't spend too much time on 2D. Depending on your computational powers, narrow it down to 2 / 3 shape choices and then start your 3D from there. I'd probably ask myself the question "how can I justify this in 2D to the judges" if you're ever caught debating 2D vs 3D

Vyssion
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User avatar
Joined: Sun Jun 10, 2012 1:40 pm

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula 1

Post by Vyssion » Fri Jan 06, 2017 1:44 pm

timhuang77 wrote::D Hi all,

I'm on an FSAE team trying to start Aero simulations for our car this year. I run Star-CCM+ v11 and are getting more and more familiar with CFD analysis. My question being: Where is the line drawn between 2D and 3D simulations? I understand that 3D is better at simulating viscous effects and estimating downforce and drag numbers. Currently, most of the vehicle simulations are done in 3D and ideally some would be done in 2D (as it is magnitudes faster computationally speaking). Our airfoil selection is done in 2D, but I would like to do more to speed up and simplify the process. Thanks
2D is good for initial aerofoil designing and to some extent, rough diffuser angle'shape testing. Beyond that, you cant really do much else with it as there are so many 3D effects (i.e. vortices) which you simply can't ignore when designing a vehicle. If you are serious about simplifying the process a bit, then what I would do is break the car symmetrically along its longitudinal axis to half solver time, and then if that still isn't enough, look at designing your front wing or rear wing in isolation as a smaller 3D simulation. Once you're happy with that, plug it all into the same model and simulate it all together and see what happens and adjust the design accordingly. but I would be careful with 2D things and the "numbers" you get out of it - I would only work in deltas; that is, "this design has a higher number than this one, therefore it is better". You can't really say that this 2D aerofoil gives me 1234.56789 Newtons of force where as the old one was only 1234.0000 Newtons, therefore its better.
If you can't explain it simply, then you don't understand it well enough.
The great thing about facts is that they are true, whether or not you believe them. - Neil deGrasse Tyson
Vyssion Scribd - Aerodynamics Papers
G&K

keroro.90
1
Joined: Mon Jul 01, 2013 8:32 pm

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula 1

Post by keroro.90 » Tue May 02, 2017 11:34 am

timhuang77 wrote:
Fri Dec 02, 2016 1:54 am
:D Hi all,

I'm on an FSAE team trying to start Aero simulations for our car this year. I run Star-CCM+ v11 and are getting more and more familiar with CFD analysis. My question being: Where is the line drawn between 2D and 3D simulations? I understand that 3D is better at simulating viscous effects and estimating downforce and drag numbers. Currently, most of the vehicle simulations are done in 3D and ideally some would be done in 2D (as it is magnitudes faster computationally speaking). Our airfoil selection is done in 2D, but I would like to do more to speed up and simplify the process. Thanks
I think depends strongly on what type of solver you're going to use...If you are going to use a very accurate approach with or without closure model like a DNS or a LES you will find some big difference....while if you use a RANS, the differences will be less...