[MVRC] Mantium Virtual Racecar Challenge 2023 (Grand Prix Cars)

[spacehead3]

from where exactly 150 mm ?

That's roughly the maximum they were running with the old high rake cars

[variante]

I don't see any reason to impose rake or ride height restrictions. Extreme rake or ride height gives no advantage.
Meshing issues are the only possible concern, which the CFD guy should deal with.
I tested the car touching the ground, and i report no issue. The plank fuses with the ground, and that's it.

Bodywork (not) penetrating the ground is the only limit we should give ourselves.
What do to when cars don't comply with that before a race? Just raise them until they do, and give a warning.

[CAEdevice]

I don't see any reason to impose rake or ride height restrictions. Extreme rake or ride height gives no advantage.
Meshing issues are the only possible concern, which the CFD guy should deal with.
I tested the car touching the ground, and i report no issue. The plank fuses with the ground, and that's it.

Bodywork (not) penetrating the ground is the only limit we should give ourselves.
What do to when cars don't comply with that before a race? Just raise them until they do, and give a warning.

Touching the ground for sure is not a issue (the tunnel is quite higher) for meshing, but a plank clearance lower than 10mm could be.

10°- 12°degree rake might be interesting from an aero point of view, but not realistic about mass distribution (the gearbox would be raised by 700mm ). If we are not going to simulate mass distribution, I would suggest:

* max rake angle: 2.5°
* min distance from planck to ground: 10mm

[beschadigunc]

I don't see any reason to impose rake or ride height restrictions. Extreme rake or ride height gives no advantage.
Meshing issues are the only possible concern, which the CFD guy should deal with.
I tested the car touching the ground, and i report no issue. The plank fuses with the ground, and that's it.

Bodywork (not) penetrating the ground is the only limit we should give ourselves.
What do to when cars don't comply with that before a race? Just raise them until they do, and give a warning.

I agree it seems like extreme rideheight doesnt seem to help , oddly though I suspect its due to low mesh resolution and general CFD setup issues, ( thought no ones fault as this challenge and its CFD isnt meant to be as accurate as F1 nor reality). Normally you would expect massive gains as you get closer ( up to a certain level). And we were running really high last year. So I can see why 10mm gap limit can be not needed but at the same time 10mm is the bare minimum so that mesh is properly done on the body and the ground.

[LVDH]

I mean, one point why I suggest to simply have MFlow to set a certain ground clearance is because for one, probably lower will simply be better. So why have everyone go through the challenge of modifying one parameter in a GUI to simply find out lower is better? The case of zero clearance is actually not interesting as indeed the plank just touches the floor and the mesher can deal with it. Now what happens if we only have one or two cells between car and ground? Well, the results might be unrealistic, or convergence can be an issue. If we agree on a certain good and realistic level, I could have MFlow create mesh settings that keep things good while also keeping the cell count pragmatic. I do not mind giving you guys freedom, I just do not think that the ride height adjustment is very exiting, at this point it just means less work for me, so it is up to you. We should find an agreement latest after Easter , though.

[Koldskaal]

I tried a few different cases using standard "MVRC" settings. Slices are zoomed in on the leading edge of the plank.

No height adjustment:


Height adjustment = -20 mm:


Height adjustment = -30 mm:


Imo this means -20 mm should be the limit with no rake. The leading edge of the plank is 430 mm behind the front wheel axis. So to maintain consistent ground clearence at the planks leading edge would require additional height adjustment of around -7.5 mm / 1 degree rake.

I think it would be fine to allow any combination of rake and rideheight within a region like this:

[LVDH]

Thank you for this small study, I think it is great work. Maybe you could simply modify the refinement level on the plank. As it is the lowest part, that is what I would change in the MFlow settings. It could either be just on the sharp corners or on the whole plank a level or two finer. I guess the best solution would be a refinement box around the leading parts of the floor. But that would cost a lot in computing requirements...

[beschadigunc]

Thank you for this small study, I think it is great work. Maybe you could simply modify the refinement level on the plank. As it is the lowest part, that is what I would change in the MFlow settings. It could either be just on the sharp corners or on the whole plank a level or two finer. I guess the best solution would be a refinement box around the leading parts of the floor. But that would cost a lot in computing requirements...

I believe increasing base size a little but refining the leading edges generally would be a worthwhile trade

[LVDH]

OK,
so I have put a slightly modified version of MFlow up. Also I noticed that while I always supply a version number in the Wordpress Download plug-in, this does not seem to show up, so you might like the improved format.
The modifications include:

• Modified WT floor height

• Modified warnings for pitch settings

• Increased edge refinement around the plank

These improvements might not work as intended.
The modified floor height should lead to a contact patch that you might perceive as more realistic. This can however cause issues with solver stability.
In previous versions, MFlow would only allow rake / pitch settings between 0 and -1.5 deg. This is now widened to -2deg. While I like the ideas from Koldskall on how to limit the ride height, I was not able to implement a good warning into MFlow, so for now, you will have to make sure the ride height stays within the proposed limits.
The increased edge refinement on the plank only slightly affects mesh size.
So please have a look and let me know if this now works as intended. I think, apart from the missing warning on the ride height, this will be how we will be using MFlow for the first race.

I am also working on the CAD files. I was not able to get it done and at this point, it will have to wait until Sunday or Monday. The modifications will affect the gearbox, exhaust and the front suspension. Sorry, I am not able to get this done earlier.

[lynch]

Hello,

I am preparing my setup for start the car development, can you please tell me if enforced to use MFlow for testing or if you can provide the setup for run the tests under openfoam without using MFlow?

Best regards,
João

[beschadigunc]

I was not able to implement a good warning into MFlow, so for now, you will have to make sure the ride height stays within the proposed limits.

Maybe just put a colored transparent plane where the 10 mm from the ground is so we can visually inspect

[beschadigunc]

Hello,

I am preparing my setup for start the car development, can you please tell me if enforced to use MFlow for testing or if you can provide the setup for run the tests under openfoam without using MFlow?

Best regards,
João

You dont have to use MFlow ( which uses openfoam anyways), but if your results don't match up with Organizers their results will count. So be aware of correlation issues

[lynch]

Hello,

I am preparing my setup for start the car development, can you please tell me if enforced to use MFlow for testing or if you can provide the setup for run the tests under openfoam without using MFlow?

Best regards,
João

You dont have to use MFlow ( which uses openfoam anyways), but if your results don't match up with Organizers their results will count. So be aware of correlation issues

Thanks for your answer,

It's possible to provide the mesh generation dictionary and inlet velocity boundary condition ?

[LVDH]

OK, small updates:
I wanted to update the gearbox and suspension. However, I am still not happy with what the updated suspension delivers, so I have to scratch that for now. I will get back on this as soon as I have the results of the first round. I will try to use those to then create a new front suspension, that will hopefully at least make a few of you happy. So for now, you have to live with the suspension we have.
I felt only upgrading the gearbox was not worth anybodies time, so until we do get a bigger update on the CAD files, this will wait.
I have updated MFlow, though. It now warns you, if the car is too low after rotating it. Also the rules have been updated. You will have a minimum ground clearance of 20mm.
As it is about one month to go, this should now be our setup.

It's possible to provide the mesh generation dictionary and inlet velocity boundary condition ?

Your friendly competition has warned you, this might not be the best idea, but here are some files:
https://mantiumchallenge.com/mvrc_files ... kPGT3XBaSg
There are some people who do use commercial software though, so it can work...

[yinlad]

OK, small updates:
I wanted to update the gearbox and suspension. However, I am still not happy with what the updated suspension delivers, so I have to scratch that for now. I will get back on this as soon as I have the results of the first round. I will try to use those to then create a new front suspension, that will hopefully at least make a few of you happy. So for now, you have to live with the suspension we have.
I felt only upgrading the gearbox was not worth anybodies time, so until we do get a bigger update on the CAD files, this will wait.
I have updated MFlow, though. It now warns you, if the car is too low after rotating it. Also the rules have been updated. You will have a minimum ground clearance of 20mm.
As it is about one month to go, this should now be our setup.

It's possible to provide the mesh generation dictionary and inlet velocity boundary condition ?

Your friendly competition has warned you, this might not be the best idea, but here are some files:
https://mantiumchallenge.com/mvrc_files ... kPGT3XBaSg
There are some people who do use commercial software though, so it can work...

For simplicity/clarity, does that equate to -20 Ride height for a 0 rake car compared to the default starting position?