Khamsin Virtual Racecar Challenge 2015

[CAEdevice]

Merry Christmas to the KVRC staff and to each team and designer!

[MadMatt]

Same to you and all other KVRC people!

[cdsavage]

Hope everyone had a great Christmas.

There are a couple of things I wanted to bring up before finalising the rulebook. Like I've mentioned before, the diffuser could be made slightly smaller - my preference is a slight reduction on height and maybe bringing the starting point slightly further rearward. The other change is to regulate the free areas at the sides of the floor - we originally wanted to keep this fairly free, but I think there's the possibility to end up with some odd-looking designs. We could regulate this area like we do with the diffuser, with a maximum height and no holes, or increase the size of the flat floor template to also cover all or most of this area.

We should make a decision on these in the next week or so, so that we can release the final rulebook.

[CAEdevice]

Hi Chris,

about the diffuser I would agree with a slight reduction on height.

About the area at the sides of the floor, I can imagine (and testing too) some very odd designs: I certainly agree with the idea of limiting the dimension (expecially the maximum height) of such "tunnels" but I'm not sure about forbidding the presence of holes (the same for the diffuser: I would prefer a smaller diffuser, 200-250mm, with the possibility of designing double channels and holes). Maybe a rule about the maximum volume/section of the concave parte (visible from below, as already done with the diffuser) could work.

A complete flat floor could be considered but including some flexibility about the rounds on the edges (F1 style).

I also have another question about the airfoils: the rule "10mm thick at least on a section" is perfect, but what about parts of the bodywork that are "air foil" shaped without being part of the wings? I mean, for example, winglets or mirror supports (but I'm sure you can imagine many other applications of the same concept): in that cases the presence of a rear edge could be allowed?

[RicME85]

Look at the supplied bodywork parts, it should answer your question.

Parts are allowed to taper to a point. This happens behind the front wheels in the supplied parts for example.

[cdsavage]

I also have another question about the airfoils: the rule "10mm thick at least on a section" is perfect, but what about parts of the bodywork that are "air foil" shaped without being part of the wings? I mean, for example, winglets or mirror supports (but I'm sure you can imagine many other applications of the same concept): in that cases the presence of a rear edge could be allowed?

Since there seems to be a lot of discussion around the interpretation of this rule, I think we will need to add some images to clear this up. As a guide, I would say that if the bodywork element remains above 10mm in thickness over half of its length, then it's definitely OK. Wing profiles will be judged more loosely, but aim for each element to be at least 10mm thick at some point along its chord. I would prefer not to put this kind of language into the rulebook, because it's a pain to have to measure everything to ensure it meets this requirement.

The rule allows a sharp trailing edge on any bodywork element, there's no language there specific to wings.

[CAEdevice]

I also have another question about the airfoils: the rule "10mm thick at least on a section" is perfect, but what about parts of the bodywork that are "air foil" shaped without being part of the wings? I mean, for example, winglets or mirror supports (but I'm sure you can imagine many other applications of the same concept): in that cases the presence of a rear edge could be allowed?

Since there seems to be a lot of discussion around the interpretation of this rule, I think we will need to add some images to clear this up. As a guide, I would say that if the bodywork element remains above 10mm in thickness over half of its length, then it's definitely OK. Wing profiles will be judged more loosely, but aim for each element to be at least 10mm thick at some point along its chord. I would prefer not to put this kind of language into the rulebook, because it's a pain to have to measure everything to ensure it meets this requirement.

The rule allows a sharp trailing edge on any bodywork element, there's no language there specific to wings.

This description you gave in the forum is ok, I would not add any word in the rulebook.

[cdsavage]

New rulebook release: http://www.khamsinvirtualracecarchallen ... lenge-2015

[RicME85]

Final release yet?

[CAEdevice]

New rulebook release: http://www.khamsinvirtualracecarchallen ... lenge-2015

Thanks. Could you confirm that the flat template has been extended rearwards? I measured it with sketchUP (that I don't know very much) because I don't have my workstation with me.

[cdsavage]

New rulebook release: http://www.khamsinvirtualracecarchallen ... lenge-2015

Thanks. Could you confirm that the flat template has been extended rearwards? I measured it with sketchUP (that I don't know very much) because I don't have my workstation with me.

Yes, the rear edge has been moved back slightly.

Final release yet?

We should be just about there. Only thing I'm not so sure about is the new rule on X-axis cross sections in the side area of the floor (template 3). Other than that, I just want to make sure we haven't overlooked anything, but otherwise this should almost be the final release.

[julien.decharentenay]

I wish you all participants and readers a happy new year 2015.

I have worked quite extensively over the holiday on refining a CFD framework for the 2015 Challenge. I took some of the issues that were apparent from the last two seasons and alleviate at least two of them:
- Parallel: the framework is based on a free version of openFoam that supports parallel processing;
- swak4Foam: this library is no longer required.

Furthermore it no longer rely on SketchUp, but take raw STL files. So (hopefully) everyone should be able to use it if they wish to. Apart from a small difference (openFoam version 2.1 vs 2.2), it will be exactly the same package that will be used for the CFD simulations in the challenge.

Important note: It is still a beta version, the meshing parameters are not yet fully finalised and it does not yet include appropriate boundary conditions for air inlet and outlet/exhausts. These will be coming shortly.

There is a webpage dedicated to it, which is very much in progress at: http://www.khamsinvirtualracecarchallen ... -click-cfd where you will be able to download it as well.

[CAEdevice]

Thank you for working on a framework!
I'm happy about the STL format too, last year I had problems with SketchUp exporting.

PS: I'd like to see that car racing : )

[MadMatt]

Very good effort! I will keep using my own CFD solution to test my designs but I appreciate your work.

Will boundary conditions of the CFD simulation be provided (wind speed, rotating wheels, etc)?

[andylaurence]

Is there a reason for using Openfoam v2.1? It's quite different to v2.3.1. Is it simply because that's what compiles on Windows right now?