[KVRC] Khamsin Virtual Racecar Challenge 2016

[HP-Racing]

That is one good looking car. Once I did an experiment with a small wing behind the cockpit as well. It did not work very well. Did you guys test yours?

Thanks! We're not really happy with the small wing's performance either.. The AoA is really low to not disturb the flow to the rear wing too much so the DF gain is minor. We'll try another variant or two but it probably won't survive until the submission.

[LVDH]

Well, that is how my mini wing development went as well. When you look at what it does to the flow on the main rear wing it just looks too ugly.
If you have too much time you could try to have the tip vortices of the mini wing attach to the underside of the main rear wing. Then you could try it massively increase the AoA of the rear wing in those areas. The vortices should help the flow to stay attached.
But I think this all will only work if you can get the vortices to attach to the underside and you increase AoA. The mini wing will probably not do anything good on its own without changing other elements as outlined.

[etsmc]

Has anyone else had issues with OCCFD particularly the snappyHaexMesh in simulation 1?
I have made a small change to my car and then exported it exactly the same a before and now a simulation is taking allot longer than usual.

Previously a light simulation would take around 8hrs. Now it has been nearly 8hrs and snappyHexMesh has not finished.

what could I have done to my model to cause this issue?

[CAEdevice]

Would it be possible that you have the "internal mesh issue"? Is your stl a closed volume? You can seen how many cell have been created in the log.

[etsmc]

that's what I though I am going to go over my model again, I must have done something.

so update.

had a look at the model and found some faces on the inside that should not be there I guess. so running another test and I have noticed in the log file when comparing to another one there are some differences.

and old log file where it has
time=500
residuals..etc.
forces aerodynamicforces output:

the new run on the other hand has
time=500
residuals..etc.
forces aerodynamicforces output:
forces frontwing_aerodynamicforces output:

and on simulation 1 the old log shows that morph iteration 1 moved mesh in 36.5s
whereas simulation 1 the new run log shows that morph iteration 1 moved mesh in 213.2s

i exported half the car from SketchUp, imported in to meshlab duplicated and flipped then merged from there its exported and then imported into netfabb and the automatic repair is done.

i have done this before, any idea why it is trying to calculate the front wing forces?


just typing this out and it may have just hit me. the file name has wing in it....

[RicME85]

Sounds like the internal issue to me, have had that when running a sim via AWS, cost me a good few quid because of a mistake in modelling.

[HP-Racing]

Has anyone else had issues with OCCFD particularly the snappyHaexMesh in simulation 1?
I have made a small change to my car and then exported it exactly the same a before and now a simulation is taking allot longer than usual.

Previously a light simulation would take around 8hrs. Now it has been nearly 8hrs and snappyHexMesh has not finished.

what could I have done to my model to cause this issue?

We had an issue with a 100% watertight model which we solved by shaving 0.1mm off the vehicle's floor.

[etsmc]

i think the file name was the culprit a new new run is currently underway and the morph iteration is doing its thing in 30 odd seconds again.

[CAEdevice]

The presence of the "wing" word also affects the mesh resolution of the component, so it is possible that the behaviour on gaps or small surfaces is different.

[LVDH]

On Linux you can always source OF and the run surfaceCheck stlfilename.
If its closed you should be fine. If not problems are not certain but possible.

[etsmc]

the issue was the file name the new new test ran and finished in the usual time. albeit with not the results I was expecting (loss in downforce and drag )

[CAEdevice]

Is there any hope to submit a car in ten days (as scheduled)?

[machin]

I'm not sure, but I'm struggling to get hold of Julien at the moment.. I presume he is just really busy with work. ...

In the mean time, I was at Goodwood Festival of Speed at the weekend and took some LMP aero photos...
https://twitter.com/rich_machin/status/ ... 4022672384 https://twitter.com/rich_machin/status/ ... 5496194048 https://twitter.com/rich_machin/status/ ... 3992107008 https://twitter.com/rich_machin/status/ ... 2496373760 There was also a sportscar from Elemental which had some nice aero details, particularly the front diffusers:-
https://twitter.com/rich_machin/status/ ... 0994176000

[AratzH]

Really nice pictures Machin!

I have always found fascinating that that front "blown" diffuser can equal the performance of Audi's full front wing.

[cdsavage]

Is there any hope to submit a car in ten days (as scheduled)?

I still haven't heard anything from Julien so I'd say that KVRC is on hold until further notice. Does anyone have contact details for him other than his KVRC and personal (gmail) email addresses? If so, could you please PM me.