[MVRC] Mantium Virtual Racecar Challenge 2019 (Grand Prix Cars)

[LVDH]

I have worked on a few parts tonight and scaled them down using paraview instead of the garbage way I did it before. The parts worked out a lot better using that method.

I'm just kicking off a new MFlow run overnight to see how far it gets by the time I wake up. I changed mflow back to 4 cores in case 6 was causing an issue for some reason. Christian also DMd me and mentioned that sometimes a run can bug out and the time intervals end up taking about 10x longer than they should, so perhaps I ran into that on my first run attempt.

Also thanks all for being so helpful, it's really appreciated! Soon I'll be able to confirm my suspicions that I have no idea about aero design

So, I checked your log files. Your mesh has about 15e6 cells. It should be around 5.5e6. So your mesh is way too big for some reason. This can happen because your geometry is somehow open. No idea why this would be the case on the CCE car as it works perfectly fine. And just an open front wing would not explain the mesh count. You can have a look at this:
https://mantiumchallenge.com/locating-h ... mulations/
Other aspects of your log make me suspect that your are not using the correct template. Please make sure to use MVRC_Fast and the hit the Build_Case button before running. In the folder of your MFlow.exe there is another log file. You can send that one as well after creating and running a new case.

Often a problem is that the geometries are open and mesh leaks inside which causes the mesh to be too big and your system to run out of memory.

I think this must be what happens to me sometimes. I have many parts that overlap each other, could this confuse the mesher?
I usually just use the stls as exported by solidworks. So they shouldnt be open, but who knows.

Designing your car with closed but intersecting geometries is the way to go. You could create a wing by extruding the separate profiles right into the center of the end plates. Having the end surfaces of the wing profiles just touch the surface of the end plates could create an issue as a super small gap is possible.

[yinlad]

I have worked on a few parts tonight and scaled them down using paraview instead of the garbage way I did it before. The parts worked out a lot better using that method.

I'm just kicking off a new MFlow run overnight to see how far it gets by the time I wake up. I changed mflow back to 4 cores in case 6 was causing an issue for some reason. Christian also DMd me and mentioned that sometimes a run can bug out and the time intervals end up taking about 10x longer than they should, so perhaps I ran into that on my first run attempt.

Also thanks all for being so helpful, it's really appreciated! Soon I'll be able to confirm my suspicions that I have no idea about aero design

So, I checked your log files. Your mesh has about 15e6 cells. It should be around 5.5e6. So your mesh is way too big for some reason. This can happen because your geometry is somehow open. No idea why this would be the case on the CCE car as it works perfectly fine. And just an open front wing would not explain the mesh count. You can have a look at this:
https://mantiumchallenge.com/locating-h ... mulations/
Other aspects of your log make me suspect that your are not using the correct template. Please make sure to use MVRC_Fast and the hit the Build_Case button before running. In the folder of your MFlow.exe there is another log file. You can send that one as well after creating and running a new case.

Often a problem is that the geometries are open and mesh leaks inside which causes the mesh to be too big and your system to run out of memory.

I think this must be what happens to me sometimes. I have many parts that overlap each other, could this confuse the mesher?
I usually just use the stls as exported by solidworks. So they shouldnt be open, but who knows.

Designing your car with closed but intersecting geometries is the way to go. You could create a wing by extruding the separate profiles right into the center of the end plates. Having the end surfaces of the wing profiles just touch the surface of the end plates could create an issue as a super small gap is possible.

Hmmm how strange. I'm using mflow 1905 because 1910 always throws an error when trying to run the case.

I'm 99% sure I'm running mvrc_fast but will double check when I get home and send you the other log file too. Thanks again.

[LVDH]

Well use 1910 and lets fix what might be wrong there. But I can see from the log that right away your background mesh is wrong. If you have a file called solver_settings.ini in your input_files folder, delete it, then rebuild and run the case.

[yinlad]

Well use 1910 and lets fix what might be wrong there. But I can see from the log that right away your background mesh is wrong. If you have a file called solver_settings.ini in your input_files folder, delete it, then rebuild and run the case.

I'll try 1910 again this evening! I did made sure the run last night was a completely clean build, but yeah I'll give 1910 another go

[yinlad]

Ok, so looking at the car in mflow-1910, I can see that the car is only have in the box that is present. I'm assuming this isn't a good thing!

https://i.imgur.com/cq7caGT.png

If I try and load an intro class LMP car it throws errors about the car that you'd expect, wheel position etc. It doesnt throw errors for the Formula car.

The car is set in position according to the original freecad files from machin and when imported together with the mandatory parts line up, so I'm not sure why it would then be out of position in mflow?

With a fresh copy of mflow1910 I'm still receiving error 'Error: Cannot run "runFile"!' having compared the runFile generated by both 1905 and 1910, they produce the same file. So I don't know why it's a problem for 1910

[CAEdevice]

Ok, so looking at the car in mflow-1910, I can see that the car is only have in the box that is present. I'm assuming this isn't a good thing!

https://i.imgur.com/cq7caGT.png

If I try and load an intro class LMP car it throws errors about the car that you'd expect, wheel position etc. It doesnt throw errors for the Formula car.

The car is set in position according to the original freecad files from machin and when imported together with the mandatory parts line up, so I'm not sure why it would then be out of position in mflow?

With a fresh copy of mflow1910 I'm still receiving error 'Error: Cannot run "runFile"!' having compared the runFile generated by both 1905 and 1910, they produce the same file. So I don't know why it's a problem for 1910

If you installed BlueCFD, try with the command line "bash runCase.sh" in blueCFD terminal

[yinlad]

If you installed BlueCFD, try with the command line "bash runCase.sh" in blueCFD terminal

yup that worked. I guess I'll just let it run and see if it completed in a reasonable amount of time? haha

[Koldskaal]

Ok, so looking at the car in mflow-1910, I can see that the car is only have in the box that is present. I'm assuming this isn't a good thing!

Some templates assume symmetrical flow, and only simulate the righthand side of the car. So this is OK.

[yinlad]

Ok, so looking at the car in mflow-1910, I can see that the car is only have in the box that is present. I'm assuming this isn't a good thing!

Some templates assume symmetrical flow, and only simulate the righthand side of the car. So this is OK.

I thought that might be it. But good to know. In which case I'll try and run directly from bluecfd overnight again and see if there is any progress. Though I still don't know why my mesh is so big. Perhaps because I ran with mflow 1905 last time

[yinlad]

If you installed BlueCFD, try with the command line "bash runCase.sh" in blueCFD terminal

this seems to be working quite well. Had a run going for about 20 minutes at most and it's already built the mesh and at time = 116! We may have made progress haha

[LVDH]

So guys, we are coming to the last submission of this season. You have one weekend to go. I just sent out the email with all the details. If you did not receive it, drop me a message, so I can manually send it.
Good luck to everyone, I hope we see a close championship battle.

[Alonso Fan]

Hi sorry to say that for the last race I'm withdrawing my car. I've learned a lot but not had time to update anything. So I take this decision to hopefully come back stronger at the beginning of next season

[CAEdevice]

I have a doubt: do not take risks and be satisfied with the performance of the car I sent (R5S2), or send a further evolution (R5S3), without having finished the simulation?

... finally: I will race with the R5S2, the running simulation seems to have a good efficency but a bit too risky about balance and cooling.

[wb92]

I have a doubt: do not take risks and be satisfied with the performance of the car I sent (R5S2), or send a further evolution (R5S3), without having finished the simulation?

... finally: I will race with the R5S2, the running simulation seems to have a good efficency but a bit too risky about balance and cooling.

@CAEdevice - no risk, no fun

I've noticed that you've made 3 evolutions? I put lot on last card and made easily 25 different geometries. However noticing a massive issue in the concept I dropped last two days and prepared a car that (more than hopefully) will secure 5th place in general classification. With a bit of luck - maybe there could be a podium, but don't think so.

@LVDH - would it be possible to see the forces from radiators itself in the future?

[CAEdevice]

@CAEdevice - no risk, no fun

I've noticed that you've made 3 evolutions?

No I made more than 3: from the previous race I launched about 10 simulations, but only the last three versions were candidate to be submitted (and only 2 actually were submitted).

Anyway, the new features for this race are:

1) a hole in the diffuser: it does not work as a double diffuser, on the contrary, it blows air into the diffuser, in a volume where I have dirty air

2) New, slightly more efficent, rear wing

3) Batwing (angles different from what we see in F1, but they have a very different use of rake compared to what we are allowed)

4) New bargeboards (an evolution of the same concept)

5) Small local details