hi
when I emit fluid using a moving object as the source, how to inherit the source velocity accurately ? the only thing i can do now is setting a vel field and apply the field to the emitted fluid but i can't get the result i want.
some tips? thanks

Do you have a Trail SOP applied to your deforming geometry set to compute Velocity?

If you are, then please post a file. Point Velocities should be passed in to the source fluid particles.

hi jeff,
thanks for the reply, yes i have applied a trail sop after the animated object,its a very simple sceen with an animated box and the box emit flip fluid using fluid source , but the fluid still not inherit the velocity.i will attach the file as soon as i can.

btw im using h12.5

i test that again and the “problem” has been solved ,the fluid is emitted at 1'st frame and i found the velocity is not calculated at that frame,when i change the emittion frame to 2,everything is ok,
thanks again

Good you got it going. I still have a question.

No velocity at the first frame because there is no velocity at that frame calculated by the Trail SOP? Can you see if the Trail SOP is calculating v at frame 1?

There is the velocity calculation option that defaults to frame forward. Try central difference or backward to current frame and see if that can calculate v at frame 1, if that is the issue.

Also, you might have to uncheck Evaluate within Frame Range, depending on which scheme you choose for calculating velocity. Otherwise, no velocity on the first frame.

im using $FF for the animation ， with default setting of the trail sop the velocity is 0 at 1'st frame. when i change to “central difference”or “forward difference” ,i can get the velocity .
And when i uncheck the “evaluate within frame range” ,i can get the velocity as well .

thank you guys so much.