Bifrost guided sim issue

[Anonymous]

When attempting a guided simulation in Maya 2018 (BOSS mesh), the particles begin by adhering to the guide perfectly, but over time follow the mesh less and less until after 400 frames or so when the particles ignore the guide nearly entirely. This seems to be the case no matter what settings I change, or what examples I attempt to replicate from the helpdocs.

Is there any established procedure for making the particles stick to the guide over time? The particles will appear to follow the guide if I turn on continuous emission, but then I end up with too much fluid, and the tutorials which exist suggest leaving this off for guided ocean sims.

Thanks, 

Jamie

[Grahame_Fuller · Accepted solution]

Hi Jamie,

This can happen if the guide mesh's motion is unrealistic, and creates excessive velocities in the simulation. This might be the case, for example, if Wave Height in the BOSS attributes is significantly higher than 1.00, or if there are scale differences between BOSS and Bifrost.

One thing that can help a bit is to set Blend With Guide to 1.00 in the Emission section of the Emission Region's properties to 1.00. This creates a fall-off between the boundary of the emission region where the particles follow the guide and the center where the physical simulation has a stronger effect.

Another thing that some people do is to use the guide mesh as a Motion Field too, with Along Normal set to a negative value so that it pulls towards the mesh's surface.

Also, whenever using a BOSS output as a guide, make sure that Use Horizontal Displacement is on in the BOSS solver so that the motion is not only vertical.

But ultimately if the guide motion is unrealistic, there's only so much that you can do to compensate.

I hope that helps,

gray