Khamsin Virtual Racecar challenge 2013 (CFD model racing)

[RicME85]

third toolbar down, the circle with the flowlines around it.
need to make sure that the eye is ticked for the original vtk as well as streamtracer.
under the properties for streamtracer you can change the number of lines and their grouping using 'number of points' and 'radius'

[AratzH]

Very nice to see some results. Also great work from all the teams with the updates.
Looking a little in the VTK file I can see that not all the details have been modeled in the CFD. Apparently the smallest mesh cell element was bigger than the gap between the front wing elements. In the attached picture you can apreciate this detail.



I don't know if other teams had a similar problem, but in this case is of special concern since it cancels any benefit of having a multi element wing. I know that making a finer mesh increases the computational time but, if the cells we see in the VTK file are the CFD ones, I would sugest using a bigger size mesh for the global car and then use refinement in the highly detailed areas such as wings. The next picture shows an example of what I mean.



I'm not really sure of how this can be done with the software you are using I think it would be worth thinking about it.
In any case it was a great job you did simulating all the cars. I can't wait to see the final results!

[astracrazy]

what gap size are you using between your elements? it should be around the 10mm mark

[cdsavage]

The same thing has happened on my front wing, but I think that the VTK file has been down-sized from the actual mesh used for the simulation. The pressure plot on the underside would tend to indicate that the slot gaps were working.

[astracrazy]

ye cdsavage is right actually, you would be able to tell from the pressure plot if its actually taken the gap into account

[AratzH]

It depends on which wing element, but it is in the 6-10mm range for the front wing and 15mm for the rear. The value is usually in the range of 3-6% of the chord of the preceding element.

You are rigth, the pressure distribution, and the downforce figures I got on the Magny Cours test point out the gaps are working. I just looked strange to see the gaps closed.

[variante]

Talking about gaps we need to reach the essential question (that i ask to Julien): which mesh size was (and will be) used for the body of the car?

I'll throw a wrench in your contest, and maybe someone can come out with an interesting idea. The way those cars are only CFD'd, and only the center of pressure is taken into account, there is no penalty for raising the center of gravity (set to a default value in Machin's simulation, right?), so no need to have bulky (heavy) things as close to the floor as possible.

Yep, that is something i thought about, but i decided to discard this chance without regrets. You'd be amazed to see how there's almost nothing that can be raised with aero benefits. For example: we could try to raise the nosecone, but we all have a problem with front downforce. We could raise the sidepods even more than Toro Rosso last year, but we would sacrifice important benefits coming from sidepods' downwash.

[astracrazy]

I'll throw a wrench in your contest, and maybe someone can come out with an interesting idea. The way those cars are only CFD'd, and only the center of pressure is taken into account, there is no penalty for raising the center of gravity (set to a default value in Machin's simulation, right?), so no need to have bulky (heavy) things as close to the floor as possible.

ye i also thought about this but there is nothing to raise for a benefit beyond what a standard design has. the cog isn't taken into account (set as default) because there is nothing we can change anyway, its just purely aero based. We don't have internal parts apart from engine and gearbox which are fixed.

What did you have in mind though or were you just putting it out there?

Talking about gaps we need to reach the essential question (that i ask to Julien): which mesh size was (and will be) used for the body of the car?

i spoke to julien about this a while back via email and i'm sure he said 0.01 is used. so gaps between elements would be taken into account

[N12ck]

Results are up!

https://www.dropbox.com/s/j07q0ra2xtpss ... 0Monza.pdf

[machin]

Awesome work, and some good results there....

I hope you don't mind me uploading a picture?!

[RicME85]

seems I need to take some design tips off Blindblom F1

[Markus]

seems I need to take some design tips off Blindblom F1

What have I missed?

[N12ck]

Hi Richard (Hit Reset)

your issue is lack of front down force, I would advise going back to basics with the front wing, and just focus on the wing design on the front for now, the KVRC car has the same issue, as you can see this is due to under-estimating the performance of the rear wing on my particular design.

Thanks
Nick

[variante]

Ric, you have a huge problem with your front wing and nosecone: their performance has decreased a lot race after race since Monaco. Solve it and you'll see your car climb a lot of places.

Markus, I think Ric just wanted to say that you still need to figure out how to design a couple of things...and i can't disagree (i'm especially referring to the 3rd element of your front wing). Good job, BTW, quite an improvement in those numbers.

As for me:
updates worked as my crystal ball predicted, however i should have gone for a lower DF setup.
Seems like my biggest problem, in comparison to JJR and CSR, is the diffuser...mine is miles behind...

[Markus]

Markus, I think Ric just wanted to say that you still need to figure out how to design a couple of things...and i can't disagree (i'm especially referring to the 3rd element of your front wing). Good job, BTW, quite an improvement in those numbers.

Yea I figured it out too. You are completely right, and that´s why I´m in this competition.
And I´m probably my biggest critisizer, everything on my car needs improving both modeling wise and aerodynamics wise.