What's new What’s new in Houdini 9: Fluid simulations

Houdini’s dynamics engine now includes solvers for various types of particulate and fluid simulation. These simulations can interact with other dynamics, such as rigid bodies, to create very complex simulations.

Smoke simulates gaseous entities such as smoke using a density field. The Smoke object creates a density field from an existing volume primitive (the default geometry is a unit sphere of smoke). The Smoke solver simulates the motion of the smoke given buoyancy, temperature across the field, and vortices.

For a quick start on how to use the smoke tools see Smoke from Object and Smoke Container.

For examples of how to use these tools see the Smoke Object node help.

Fire simulates fuel combustion, releasing heat and gas. It produces a flame as well as the resulting smoke and soot. It uses a Smoke object and Smoke solver like the Smoke tools do, but with different default settings.

For a quick start on how to use the smoke tools see Burst Into Flame and Fire Container.

For examples of how to use these tools see the Smoke Object node help.

Volume based fluid simulates fluids such as water using a sign distance volume. It produces a glue-like liquid that is confined to a fixed box. The Fluid object creates a tank for fluids (the default object is a half-filled tank of water).

For a quick start on how to use the volume based fluid tools see Liquid from Object and Liquid Container.

For examples of how to use these tools see the Fluid Object node help.

Particle based fluid simulates fluids using a field of particles. It produces a splash-like liquid that can move anywhere in the scene. The Particle fluid object creates particle volumes based on existing geometry (the default object is a cube shaped volume).

For a quick start on how to use the particle based fluid tools see Particle Fluid from Object.

For an example of how to use this tools see the Particle Fluid Object node help.

There is also a tool that can generate fluid from an object and another that can absorb fluids.

For a quick start on how to use the source and sink see Source from Objects and Sink from Objects.

For an example of how to use these tools see the SourceAndSink example on the Fluid Object node help card.

There are a variety of forces you can apply to both volume based and particle based fluids. These forces include:

• Surface Tension

• Viscosity

• Visco-elasticity - the fluid “remembers” its original shapes and tries to return to it.

• Vorticles - small particles that apply paddlewheel forces to the fluid, preventing vortices from dissipating.

• Gas Emission - releast gas into the simulation causing everything to move away from the location. For example, an explosion where everything moves away from the explosion center rather than conserving volume.

For an example of Surface Tension see the TeapotUnderTension example on the Gas Surface Tension node.