Houdini 21.0 Fluids

FLIP Configure Tank

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Houdini’s SOP FLIP fluids provide several ready-to-use tools to illustrate some of most common workflows. To access the tools, create a Geometry SOP node and double-click it to dive into the operator. There, press the ⇥ Tab key and enter flip configure. From the list choose FLIP Configure Tank. Houdini creates a complete network and you can immediately start the simulation by clicking the icon in the playbar.

The FLIP Configure Tank tool shows how to

The tool adds a container with default dimensions and a narrow band waterline. This setup represents a basic setup and can be used as a starting point for more complex networks.

Main nodes

Node name Function

fliptank1

FLIP Container SOP. This nodes creates a domain where fluid simulation happens. At the domain’s boundaries, particles are sourced and deleted to maintain an equilibrium. You can also connect an object to the node’s input. This object will then serve as a custom-shaped domain. The FLIP Container is also the place where you turn on physical properties like Surface Tension or Viscosity. You can also define custom attributes such as temperature or density. If you want to increase the number of particles, decrease Particle Separation.

flipsolver1

FLIP Solver SOP. This node is the center piece of the network and brings everything together to simulate the fluid’s behavior. The Waterline tab is of particular interest: when the Waterline is turned on, the solver creates an even particle surface. In simulations, where the particles interact with the domain’s limits, Boundary Conditions are relevant.

particlefluidsurface1

Particle Fluid Surface SOP. Turn on the node’s Display/Render flag to invoke the creation of a polygon mesh, representing the fluid.

Tips

To...Do this

Change the container size

Adjust the fliptank1 node’s Size parameters or connect a custom object to the node and scale it accordingly.

Change the container geometry

Create or load an object and connect it to the fliptank1 node’s input. You can use any closed object or volume as a container.

Create more particles

In the fliptank1 node you can find the Particle Separation parameter. Decrease the default value to get more particles. Note that small values increase simulation time and memory usage.

Use viscosity and/or surface tension

In the fliptank1 node, turn on Surface Tension and Viscosity. Expand the sub-panels and enter new values for Surface Tension and Viscosity.

Display particles instead of spheres

Go to the flipsolver1 node’s Visualization tab and turn off Points as Spheres.

Fluids

For beginners

SOP WORKFLOW

Particle Fluids (SOP)

Viscous fluids (SOP)

Optimization (SOP)

FLIP Configure tools (SOP)

DOP WORKFLOW

Particle Fluids (DOP)

Viscous Fluids (DOP)

Oceans (DOP)

Optimization