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

[G-raph]

You can see the cooling layout and entire floor and diffuser profile in these images as low opacity ghosts

Fair point, that's indeed revealing quite a bit. It's just a shame that the most interesting thing on a CFD picture is the ghosted geometry.

In any case, something very special might happen for the final race.

Sounds exciting!
It could be yaw simulation as already mentioned, or maybe a more refined mesh with more detailed post-processing?

[yinlad]

Troubleshooting time! I have Sims running fine on the fast preset. But if I try the standard settings, after about 500 iterations the values (cd, cl) runaway exponentially, up into the thousands until the simulation fails. Has anyone experienced this before?

[CAEdevice]

Troubleshooting time! I have Sims running fine on the fast preset. But if I try the standard settings, after about 500 iterations the values (cd, cl) runaway exponentially, up into the thousands until the simulation fails. Has anyone experienced this before?

It happened to me when I had a geometry gaps or bad STLs

[yinlad]

Troubleshooting time! I have Sims running fine on the fast preset. But if I try the standard settings, after about 500 iterations the values (cd, cl) runaway exponentially, up into the thousands until the simulation fails. Has anyone experienced this before?

It happened to me when I had a geometry gaps or bad STLs

Interesting that it works ok on the fast settings! I'll probably have to spend some time figuring out which part is causing the problem and go from there

[CAEdevice]

Troubleshooting time! I have Sims running fine on the fast preset. But if I try the standard settings, after about 500 iterations the values (cd, cl) runaway exponentially, up into the thousands until the simulation fails. Has anyone experienced this before?

It happened to me when I had a geometry gaps or bad STLs

Interesting that it works ok on the fast settings! I'll probably have to spend some time figuring out which part is causing the problem and go from there

With raw setup, snappyHexMesh has to manage bigger cells during castellation and refinement

[LVDH]

Yes, Matteo is turning into an OF expert.
I have been quite productive the last few days with MFlow development. One feature will be a direct check for open geometries.
Currently MFlow also creates a small script called check_closed_stls.sh. It is not great but maybe it helps in your case.

[CAEdevice]

Yes, Matteo is turning into an OF expert.
I have been quite productive the last few days with MFlow development. One feature will be a direct check for open geometries.
Currently MFlow also creates a small script called check_closed_stls.sh. It is not great but maybe it helps in your case.

Ahah, no, only bad STLs expert

[yinlad]

Freecad Mesh workbench, Analyze -> Check Solid Mesh. I think that has just saved me a lot of time!

[beschadigunc]

Yes, Matteo is turning into an OF expert.

Matteo you should really quit OF , not healthy for your relationship.

[G-raph]

So now is the time to refit the high downforce wings, watch Variante win the last 2 races while I finish P2 and seal the championship, right?

Yeah, but that's not really fun.

Therefore, for Race 04 I've decided to take a risk and rework the entire floor! It gives a modest downforce increase with the fast settings (+0.1Cl) but I think it has potential for larger gains with the official simulations... unless I've overcooked it and all the vortices under the floor blow up of course!
We'll find out, but in any case I'm quite curious to see what it will do.

So here is my Race 04 car, with the customary GIF comparison to Race 02 (as it doesn't make sense to compare to Monza) :



- Refitted Monaco RW, but with a smaller beamwing.
- Slightly reduced Front Wing Flap chord to move balance rearwards, closer to optimum.
- Subtle reshaping of the sidepods, with slightly higher leading edge and double-element sidepod vanes.
- Smaller cooling exit panel (but not as much as for Monza) as there is margin to the cooling requirement.
- Additional vane along the coke line to (hopefully) fix the flow separation seen in the official simulations.
- Brand new floor as mentioned above, including the small edge details from the Monza configuration.

Finally... bonus points for whoever finds the cheeky innovation / loophole that I have stolen from another competitor!

Good luck everyone!

[CAEdevice]

it's impressive to see that the car has changed very little from the first race to today, with the exception of the Monza setup and the new floor... and congratulations for the courage to submit a car calculated only with the "fast" template.

For the loophole I ask for a little help: is it visible in the image (maybe the second cut on the diffuser side?) or do we have to imagine it in the area under the car?

[yinlad]

it's impressive to see that the car has changed very little from the first race to today, with the exception of the Monza setup and the new floor... and congratulations for the courage to submit a car calculated only with the "fast" template.

For the loophole I ask for a little help: is it visible in the image (maybe the second cut on the diffuser side?) or do we have to imagine it in the area under the car?

The 2nd diffuser cutout was present Monza, the only thing I can see is the 'floating' outboard fence that is similar to something Pure Power did last race so that'd be my guess

[yinlad]

So changes for R04 are:
- R03 HDF Front Wing to balance performance found at rear of the car.
- RW evo, more aggressive flap and BW, minor RWEP adjustment.
- New rear brake duct winglets.
- New engine cover with silly sail wings. Much improved flow to rear of the car.
- Wings behind drivers head to control losses.
- Move to chimney cooling.
- Improved sidepod undercut.
- Smaller sidepod inlet.
- Proper blend between sidepod and floor.
- New floor fences to fine tune main floor vortex.
- Diffuser cut outs to control vortex shedding, but still struggling to prevent them blowing up quite early on in the diffuser. I suspect I have some blockage and loss of performance here.

I've definitely broken the -5Cl barrier now which was my R01 target, better late than never

I'm predicting around -5.2Cl on a full run. I'm expecting a close midfield so it's difficult to predict the result. Probably close run between me, CAE and Max for P4. Podium spots are still a chunk ahead, if I can address my diffuser issues then possibly closing in for the final race.

[G-raph]

For the loophole I ask for a little help: is it visible in the image (maybe the second cut on the diffuser side?) or do we have to imagine it in the area under the car?

It is visible on the GIF, and it's obviously a part that is changing from R02 to R04.

The 2nd diffuser cutout was present Monza, the only thing I can see is the 'floating' outboard fence that is similar to something Pure Power did last race so that'd be my guess

It is not that, I'm afraid.

- Move to chimney cooling.

Cooling chimney? 10/10.

Very nice tidy car otherwise. I always though your sidepod undercut looked a bit peculiar, this new one looks more sensible and elegant.

The flow over the top of G-Raph's car is outrageous, a work of art

Did the R03 CFD pictures finally convinced you to copy my engine cover shape and airbox sail? Good choice!

[yinlad]

Did the R03 CFD pictures finally convinced you to copy my engine cover shape and airbox sail? Good choice!

Yes and no. They did highlight I needed to work on flow over the top, the engine cover shape was just where keeping things attached took me. The sails are just a necessary evil now if I want to move toward the front

The sidepods were always a result of modelling limits but I've really worked on being improving that. I'm generally quite happy with them now. I'd like a few more radiused joins to tidy things up even more but our mesh sizing tends to discourage radius under 35mm or so compared to a flat 90 degree corner join