I'm recently trying to create a volume at a standstill with smoke or pyro FX like cutting through inside fog.

Just wondering if Smoke solver or Pyro solver can use Open VDB object as a source of them or there is any approaches without Open VDB…

You can use vdb grids as a source, but the simulation will only be done a normal grid. Post-sim you can convert from volume to vdb if you want.

May I ask how do I transfer that VDB to DOP using grid?
I'm sorry for the stupid question ?

You can reference a vdb volume in a fluid source, the same way you currently bring in a regular volume, just point it to your vdb grid.

Much thanks, Solitude! It works