Fluids - Emission Stop

One common question is how to stop the emission of new particles? There are several methods to do this.

Defining a Volume

Some emitters let you define a certain volume that is filled with particles:

• Emitter node > Node Params > emitter-specific section (e.g. “Circle”) > Volume
• “Sphere” and “Fill Object” have a built-in fill option.

Speed Animation

The next method uses animation keys:

• Emitter node > Node Params > emitter-specific section (e.g. “Circle”) > Speed
• Move the timeline slider to the last frame where particles should be created, e.g. frame 49. Click on the small circle next to the parameter to set a key.
• Move the timeline slider to the next frame (50 in this example) and create another key.
  

Speed Expression

If you work with an expression, the two arguments are 0.0 and the emitter's current speed. By default, this is 2.0:

• Right-click on the emitter's “Speed” and choose “Open curve”. The “Curve Editor” is being opened.
• In the large field next to "+" enter: if(f>49,0.0,2.0)
• This expression says that if the current frame is greater than 49 the “Speed” parameter will be set from 2.0 to 0.0.


Particle Limit

Another idea is to define a particle limit with

• Emitter node > Node Params > Particles > Max Particles
• Just enter a number, e.g. 75000, and the emitter will stop to create new particles once this limit has been reached (in most cases you get a few more particles).