CFD - Computational Fluid Dynamics, Motorsport, Formula 1

[flyboy2160]

......but you need a moving floor....

why do you need a moving floor if you're not modelling rotating tires?

[shelly]

because of boundary layers. And you will go nowhere without rotating tyres

[Jersey Tom]

Here's a different discussion point than usual:

What is CFD good for, and what isn't it good for? When is it an applicable designer-level tool, versus an analyst-level tool?

[shelly]

let's talk about car external aero.
You get a good idea of fow pattern, flow through radiators, wings behaviour, floor behaviour.
you miss precise vortices trajectory and dissipation, and vortex induced effects as a consquence.
But you get the overall general idea of flow interaction, so as you can test in wt.
Downforce prediction is more accurate than drag prediction, you usually underestimate drag by 10-20%

[astracrazy]

hi guys

has anyone get any articles or tips they can give me of how to analyse CFD results

for example if you run a test on an f1 car, what would you be looking far to make improvements using surface plots, flow trajectories etc. etc.

I've found my way to run a simulation, now i want to try and learn what i can understand from the results.

Thanks!

[Forza]

Some screenshots of Force India CFD (old design) from their current video Link

[flyboy2160]

because of boundary layers....you miss precise vortices trajectory and dissipation, and vortex induced effects as a consquence...

you don't need a moving floor to create boundary layers. they can be created in any viscous analysis on any surface.

modern viscous CFD is capable of analyzing vortex flow, even transient, intermittant shedding vortices. the CFD results, as always, must be validated by tunnel or road testing.

[shelly]

what I neant is that you need a moving floor to have the correct representation of the boundary layer. Car's floor and road floor maus have a relative velocity in order to achieve that. Modern rans is not thta precise in describing turbuletn flow around af1 car - you have ot take into account a certain amount of error especially on vortices.
I do not know how many full car non stationary les simulations would fit in the current fia rules limitations for flops

[flyboy2160]

....modern viscous CFD is capable of analyzing vortex flow....

and you don't need a supercomputer to see them. this is a vortex shed off a classic micro vortex generator on the wing of a plane i'm analyzing:



i'm using an hp 400z workstation and solidworks flow sim 2012.

[AeroGT3]

....modern viscous CFD is capable of analyzing vortex flow....

and you don't need a supercomputer to see them. this is a vortex shed off a classic micro vortex generator on the wing of a plane i'm analyzing:



i'm using an hp 400z workstation and solidworks flow sim 2012.

You may see a vortex in solidworks flow sim, but that doesn't mean the lift/drag and magnitude/trajectory of the vortex are correct. Personally I am highly skeptical of solidworks results, but YMMV.

[craigp46]

Here's a different discussion point than usual:

What is CFD good for, and what isn't it good for? When is it an applicable designer-level tool, versus an analyst-level tool?

CFD is brilliant at post processing results. The results can be analyzed and reanalyzed because the raw data from the simulation is held on a hard disk, on the opposite hand, wind tunnel data is limited in this respect, if you failed to take some key results from a particular area of the car on the day of the test at the tunnel, its a very expensive event to pack up and head down to the tunnel again. It also allows for prototyping aero parts. Design/Aero engineers may churn up 60 new designs that they think will improve performance. To test each on in the tunnel again is going to cost mega bucks and too much time, therefore if each one is ran on a CFD program, that 60 can be narrowed down to the 5 most promising designs which is a better prospect than 60, although still quite time intensive, on a parrallel system much less time than physical testing.

CFD is not good for repeat processes such as ride height adjustment for aero maps, or wing angles. If each simulation takes between 5 and 10 hours + grid generation, thats an awful lot of simulation time for each ride height variation, so things like this should be created in the tunnel.

[astracrazy]

does anyone know how to do the following in solidworks

i want to simulate a floor (in this case it can be static) but i don't want it to be included in the results. Normally i'd set a global goal for force y and z (downforce and drag) but won't this also take the results from the floor? This is what i don't want i just want the floor to effect the results of my model. How can i do that?

[TDH]

I have a question involving CFD in Ansys.

I need to do a 2D analysis of the DRS system. I found a tutorial online which explains how to do a 2D analysis of an airfoil. I want to follow this tutorial but I get stuck when I need to upload a text file with the coordinates in the software. Does anybody know how I can fix this?

The tutorial I'm following is:
http://www.google.be/url?sa=t&rct=j&q=& ... 3MxucuNAAw

[Jersey Tom]

I have a question involving CFD in Ansys.

I need to do a 2D analysis of the DRS system. I found a tutorial online which explains how to do a 2D analysis of an airfoil. I want to follow this tutorial but I get stuck when I need to upload a text file with the coordinates in the software. Does anybody know how I can fix this?

The tutorial I'm following is:
http://www.google.be/url?sa=t&rct=j&q=& ... 3MxucuNAAw

Have you tried contacting your ANSYS reseller / technical sales rep?

[Blanchimont]

I would guess that a some point in your text file, there is an error in the correct format that ansys needs to import the data without failing.

Check if there is a comma instead of a point, if there is a blank that makes problems.

Does the text file look like shown on page 2 of your tutorial?