how to make the particle fall speed and stop completely, filling acup

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mauroalzate
Posts: 2
Joined: Wed Jul 20, 2011 7:02 am

how to make the particle fall speed and stop completely, filling acup

Postby mauroalzate » Wed Jul 20, 2011 5:40 pm

how to make the particle fall speed and stop completely, filling a cup.
I only have a gravity deamon, and sd File from 3d max...
Thanks


mauroalzate
Posts: 2
Joined: Wed Jul 20, 2011 7:02 am

how to make the particle fall speed and stop completely, filling acup

Postby mauroalzate » Wed Jul 20, 2011 5:42 pm

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Anaxarchos
Posts: 843
Joined: Wed Mar 19, 2008 4:21 pm
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how to make the particle fall speed and stop completely, filling acup

Postby Anaxarchos » Thu Jul 21, 2011 12:00 pm

A classic...

The particles in RF are different from any common particles you ever saw in your 3D application, because they are simulating a fluid flow, the particles velocity is determined by forces and quantities such as mass, pressure, gravity etc. You better compare the RF particles with a fluid in a container in your 3D app.

The easiest way to understand how the motion of those particles works is to think it is Newtons F = ma but slightly more complicated.

What is happenng in the glass is that particles from high pressure areas are pushing towards particles in low pressure areas, so there is a constant movement in the glass.

In the background the fluid solver also makes calculations that are even enhancing this behaviour. The calculations on which most fluid simulation systems in CG are working with are based on models for the simulation of incompressible flow. This means, the volume of the fluid cloud has to stay constant. What the solver does is altering the pressures in every setp so the incompressibility condition is always fulfilled, so there is a bit of a constant movement inside that glass.

What you can do now is basically:

- Ajust Int/ Ext Pressures:

Lowering the internal pressure will diminish the forces between the individual particles.

- Add Drag

Drag kind of "sucks" momentum ot of the particles, making them settle faster.

A combination of those two plus some time to settle the particles would be the method of choice in many scenarios.

- Add a kSpeed Deamon aith Limit and Keep activated

Just remember that if you need to do something with your liquid again, you probably want the particles to be able to move again, so the Limit & Keep maybe should be Keyframed...

Hope this helps.
www.fk-fx.com


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