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This is place where the type of fluid is defined, e.g. water, honey, paint, syrup, etc. It is possible to

  • attach multiple emitters to one common "Fluid" container under "Simulation"
  • add more than one fluid per scene, but the fluids are not able to interact.

 

 

Type

There are three different fluid types available:

  • "Dumb” particles are often used for spray or foam. These particles cannot react with each other and do not have the characteristic fluid properties, but they are simulated very fast.
  • "Liquid - SPH" is a very accurate solver and provides GPU support.
  • "Liquid - PBD" is a very fast type (faster than “Liquid - SPH”) and provides GPU support.
Resolution

With this setting you can change the amount of particles. When “Resolution” is set to 1.0, a volume of 100 cm x 100 cm x 100 cm is filled with 1,000 particles. The parameter accepts any positive value.

Density

This parameter is defined as mass per volume unit and is different for each substance. “Density” does not change the fluid's behaviour, but it is possible to combine fluids from different domains, e.g. to mimic substances like oil and water. The unit is kilograms per cubic metre. The density of water is 1,000 kg/m3. Avoid very small values close to 0, because they can lead to instabilities.

Int Pressure

“Int Pressure” simulates the forces between nearby particles and pushes them apart - this makes the fluid fill a greater volume. This parameter is not available for "Dumb" particles.

Ext Pressure

“Ext Pressure tries to limit a fluid’s expansion tendency and can be compared to atmospheric pressure. This parameter is not available for "Dumb" particles.

Viscosity

Substances with very high viscosity are honey, tar or syrup, for example. Fluids with low viscosity are alcohol, many solvents or liquid gases. You can enter any positive value:

  • The default value of 3.0 describes the viscosity of water.
  • If the fluid does not behave correctly with higher settings (around 50+) you should consider increasing substeps under Scene > Solver.
  • Equal values for → "MIN | MAX Substeps" produce good results with highly viscous fluids. Try Liquid - PBD 20 | 20 or Liquid - SPH 200 | 200

This parameter is not available for "Dumb" particles.

Surface tension

A fluid's tendency to contract and create drops and tendrils is increased with higher settings. You can enter any value between 0 and 10. This parameter is not available for "Dumb" particles.

Use Initial State

Initial states can be created and activated/deactivated individually for each node (also see → "Initial States"). When

  • enabled the initial state will be used
  • disabled the initial state will be deactivated temporarily.
Create Initial State

This function lets you set any simulation frame as a new start preset. When you reset the scene the simulation will be starting from the previously defined initial state. The associated initial state file will be written to the scene's catch folder specified under Scene > Cache. Here is the workflow:

  • Simulate (click on the timeline's "Play" button)
  • Stop the simulation at any time and press "Create Initial State.
  • Set “Use Initial State” to “Yes” if necessary.
  • Rewind the timeline to frame 0; the initial state is shown.
  • Simulate.
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