PhoenixFD Force Examples

[wxyz]

Are there any PhoenixFD Force Examples available?

[Svetlin.Nikolov]

Hey,

Can you be a bit more specific? What is your setup?

Cheers!

[wxyz]

Trying to understand how it works. Working on a waterfall sim.

[Svetlin.Nikolov]

Do you mean the plain force or some other Phoenix force? I assume you have already checked the docs site and haven't found an answer?

Cheers!

[wxyz]

The one in Pflow

[Svetlin.Nikolov]

Ahhh, you mean the force operator, I see. So for a waterfall scene one pitfall I can think of is that you might want to affect particles outside the liquid volume, flying in the air. However, the operator reads the grid voxel velocity of the Phoenix simulation's cache files, and for a liquid simulation, this velocity only exists for voxels inside the liquid volume, and the empty air voxels don't have any velocity. In this case, what you need to do would be to enable Simulate Air Effects in the Dynamics rollout of the simulator and generate new caches by simulating again.

The Ignore Time Scale option is needed only in case you have changes the play speed of your simulator. The Time Source option would allow you to change the Influence of the force depending on the age of the particle - e.g. if you animate the Influence from 100 at frame 0 to 0 at frame 10, this means that newborn particles will be affected by the force with 100% Influence, and over 10 frames since the birth of the particle the Influence would decline until the fluid stops affecting the particle completely. This way no matter how early or late in the simulation a particle is born, the Influence would affect it depending on the time of its birth and not depending on the current timeline frame.

Chers!

[wxyz]

Is the Force Operator used to enhance an existing Phoenix Cache? Like adding collision spawns?

[Svetlin.Nikolov]

In general it just reads the velocity from a cache sequence and moves the pflow particles, while the cache sequence remains intact. This happens while just scrolling the timeline. You need to run an actual Phoenix simulation and eventually use the pflow particles affected by the Phoenix force as source, in order to write new cache files.