Engine Cylinder Colliders Leaking

Working on an animation of a car engine cylinder and am having issues with the colliders leaking.

It’s a small container, and have tried a voxel size of .1, substeps and pressure iterations up to 10, but still getting leaking through colliders.

There’s some high pressures to move the fluid into/oit of the cylinder correctly, maybe that’s causing it?

Anything else to try and help the colliders solid? They are all low poly and have thickness


Post up a basic setup and I will see if I can tweak it.

Thanks Paul.

I’ve been able to get it closer. Reduced the sim speed to 50% and really boosted the subframe and pressure (over 20 for both) to stop the leaking. The documentation says pressure usually stays within 2-10, but those numbers werent helping the collision problem.

EDIT: Not quite…still getting leaks.

If you’re not familiar with the basics…sim should inject air, which the piston pulls in on the first down stroke. Then it should compress it on the up stroke. Then the spark fires, igniting the air, pushing the piston back down. Then the piston pushes all the exhaust out on the next upstroke.

Here’s the project:
GW_NASCAR_EngineRig_test.c4d (447.6 KB)

I’ll have a play later today

Made some minor changes such as increasing the collision margin on the colliders but more importantly adjusting the fire shader curve to clip excess burn. I assume it is burn you wanted to render. Should easily be able to redo this with Redshift.
Second vid is the temperature version

V1GW_NASCAR_EngineRig_test.c4d (512.6 KB)

V2GW_NASCAR_EngineRig_test.c4d (512.9 KB)
V2 is a temperature render of the same sim
My TurbulenceFD Tutorial Set

Thanks for taking a look Paul.

Still getting some leaking with your setup. I will actually need to render temp/burn/density to represent intake air/combustion/exhaust

Maybe @Jascha_Wetzel has some ideas to help colliders from leaking?

1 Like

Could you post a shot and frame number of the spill?

Thanks Jascha.

I’ve updated the scene to more closely represent the actual geometry. I’m suspecting TFD was having trouble when two colliders occupy the same space, causing leaks in the intersected space.

Would be great if you were able to create areas where you could cool the fluid instead of just a global setting, effectively making kill boxes inside objects. Like setting a negative channel value would decrease the values inside that object.

Good point. A field-control feature is on the roadmap for Reactions. I hadn’t included the Decay node (i.e. cooling, dissipation) in this yet though, only force-based nodes like turbulence, wind, etc.

1 Like