I have a simple smoke solver with density and velocity volume derived from a sphere. The velocity values are {0,1,0}. I compared the merge modes ‘add’ and ‘copy’ for velocity volumes in source volume node in dop net. Following screenshots show the same with velocity streamers in xy plane.
The copy mode works as expected. Source velocity is same for every step. However, I could not get the add mode. I expected that the velocity values will be added at each step and as a result, the streamers will turn all red. However I noticed that the velocity values are added at the voxels where velocity was zero initially (i.e. above the sphere). How come velocity values are added above the sphere volume, should't it be added at the same voxels i.e. source velocity volume ? How did source velocity values appear above the sphere source as seen in screenshot above ??
I tested the add mode with density, and density gets added to same voxels and it gets denser and denser. Shouldn't it be the case in velocity volume too ?
Enivob I think that is what the Masks tab is for. If you want to mask out a specific portion of a field and have Volume Operations only affect that portion.
Yes that can be done but my question was why it adds the velocity at the empty voxels. Can you shed some light?
akshay_asarkar Yes that can be done but my question was why it adds the velocity at the empty voxels. Can you shed some light?
they are not added for empty source voxels, but your sim is probably evolving, as nondivergent projection corrects all voxel velocities you will start seeing values in all voxels even if you don't have any additional shaping
you will not see it with unmasked copy as that will overwrite all voxels every step, and doesn't allow for sim to evolve (at least in your 16.5, in H17 Clamped To Active Region would have to be unchecked)
