The Source controls the emission of fluid and where the fluid emits from, so that the simulator knows where in 3D space the fluid can be born.
An Emitter can be geometry and/or particles, and is what actually emits the fluid inside the simulation grid. The emitter(s) must be selected by the Source in order to emit fluid inside the simulator, unless you are using the Initial fill option in the simulator’s settings, or specifying a geometry to do an initial fill with liquid.
The Source also contains its own settings that determine how much fluid is emitted, what is emitted, and so forth. A Liquid Source can be used to emit fluid into a Liquid Simulator using Liquid FLIP particles, or any of the Source's Grid Channel options, and it can also emit fluid for multiple channels at once.
This includes emitting options such as RGB color and Viscosity, as well as emitting secondary particle types like Splashes, Mist and Foam.
UI Text Box
type
info
If you have many Simulators in the scene, by default each Simulator will interact with a Source's Emitter Nodes, as long as they are inside that Simulator. You can exclude Sources or Emitters from a Simulator's Scene Interactionrollout.
If you switch to use the Include List mode, you have to pick both the Source and its Emitter Nodes in the Interaction List.
The Source can emit in three different Emit Modes:
Surface Force creates fluid only at the surface of emitters
Volume Brush fills the entire volume of emitters
Volume Inject fills an emitter’s volume while adding pressure for an explosive effect
You can also use textures as masks for each of the emission channels, to create more interesting emission behaviors, with more variation. Specifically, Masks make it possible to emit unevenly from only some areas, or emit unevenly from the entire volume of an emitter.
UI Text Box
type
tip
Using textures as masks can help to break up the emission, and can lead to a more varied or natural looking result.
For example, you could use a black and white noise texture as a Mask when emitting Liquid particles, to make it so that the black parts of the texture emit nothing, while the white parts emit Liquid.
Additionally, each channel can have one or many Discharge Modifiers. They They can give you more precise procedural control over how the fluid gets emitted.
Discharge modifiers vary the emission over different parts of the emitter, depending on the properties of the emitter - e.g. the direction of its Normals, the speed of movement at each point of an animated emitter, etc
