Houdini 17.0 Shelf tools

FLIP Fluid from Object shelf tool

Creates a FLIP Fluid Object from SOP Geometry.

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This tool converts your object into a cluster of particles. FLIP fluid is a hybrid between volumetric fluid and SPH (smoothed-particle hydrodynamic) fluid because it is mainly particle based, but is solved in a grid like volumetric fluid.

FLIP fluid is used for fast moving, largely unconstrained fluid simulations, such as rivers. It is also better to use when new particles are injected into the system. SPH fluids are good for slower moving fluids, which may need to react to fast moving constraints. For example, a glass of water.

FLIP fluids give you more control over particles using POPs and are more malleable. This tool puts down a POP Solver in the AutoDopNetwork, where you can work in POPs. FLIP fluids are also faster than SPH fluids, if you don’t need to substep the FLIP fluid. If you need to substep the FLIP fluid because of fast moving colliders, you may find SPH just as a fast or faster.

FLIP fluids are useful because particles can be placed on top of each other without destabilizing the system. SPH tends to blow up if you move particles too close.

Using FLIP Fluid from Object

  1. Select the geometry object to convert to particle fluid.

  2. Click the FLIP Fluid from Object tool on the Particle Fluids tab.

    You can modify the Particle Separation on the Particle Fluid Object to control the distance between particles. A smaller particle separation will result in a greater number of particles and a higher resolution. You can also change the source object by modifying the SOP Path.

For specific parameter help see the FLIP Fluid Object node help.

FLIP vs. POPs

FLIP differs from normal particles in two ways. Firstly, it keeps particles apart. FLIP acts as a surface tension type force, that does not keep particles blobbed together. Secondly, it uses volume forces, where non-divergence is enforced. Non-divergence means that particles that are overlapping each other aren’t allowed to move towards or away from each other, but have to move as a group.

To control volume forces, you can edit the following parameters on the FLIP Solver.

  • Turn down Smoothing on the Volume Motion tab. This will let particles move more independently.

  • Turn down Force Scale on the Volume Motion tab. This controls how much the particles are corrected, reducing the volume forces.

  • On the Volume Motion > Divergence subtab, turn on the Diverge by Attribute checkbox. This lets you force the particles to separate or converge.

  • Decrease the Division Size in the FLIP Configure Object. It defaults to double the particle scale, so 8 particles average together to one cell, which is typically sufficient. However, if you make it the particle scale, you’ll get more independent particles but you will have much higher CPU and memory costs.

See also

Shelf tools

Using the shelf

  • Customize the shelf

    How to change the look of the shelf, change and rearrange its contents, and create your own shelf tools.

Shelf tabs

  • Create tab

    Tools on the Create tab let you create and place primitives, curves, and null objects in the scene view.

  • Modify tab

    Tools on the Modify tab let you easily customize objects in the scene view.

  • Model tab

    Tools on the Model tab let you edit objects in the scene view.

  • Polygon tab

    Tools on the Polygon tab let you modify polygons in the scene view.

  • Deform tab

    Tools on the Deform tab let you deform objects in the scene view.

  • Texture tab

    Tools on the Texture tab let you texture objects in the scene view.

  • Rigging tab

    The Rigging tab contains tools for creating premade rigs.

  • Muscles tab

    The Muscles tab contains tools for creating muscles.

  • Characters tab

    Tools on the Character tab let you create characters in the scene view.

  • Constraints tab

    Tools on the Constraints tab create a constraint network where you can constrain objects to each other in the scene view.

  • Hair Utils tab

    Tools on the Hair Utils tab let you quickly set up hair and fur on objects.

  • Guide Process tab

    Tools on the Guide Process tab let you influence the placement and orientation of guide hairs by painting skin attributes.

  • Guide Brushes tab

    Tools on the Grooming tab let you add and directly manipulate hair.

  • Terrain FX shelf tab

  • Cloud FX tab

    The Cloud FX tab contains tools for creating cloud effects.

  • Volume tab

    The Volume tab contains tools for creating volume effects.

  • Lights and Cameras tab

    Tools on the Lights and Cameras tab let you create and place lights and cameras in the scene view.

  • Collisions tab

    Tools on the Collisions tab let you create collision objects in the scene view.

  • Particles tab

    Tools on the Particles tab let you create dynamic particle simulations.

  • Grains tab

    The Grains tab contains tools for simulate grains of sand and other granular matter.

  • Vellum tab

    The Vellum tab contains tools for creating different types of vellum effects.

  • Rigid Bodies tab

    Tools on the Rigid Bodies tab let you create dynamic RBD objects in the scene view.

  • Particle Fluids tab

    Tools on the Particle Fluids tab let you create particle based liquids in the scene view.

  • Viscous Fluids tab

    Viscous fluids are FLIP simulations that use a temperature attribute to drive viscosity.

  • Oceans tab

    The Oceans tab contains tools for creating ocean simulations.

  • Fluid Containers tab

    The Fluid Containers tab contains tools for creating pyro, smoke, and liquid containers.

  • Populate Containers tab

    The Populate Containers tab contains tools for creating and removing fire, smoke, and liquid.

  • Container Tools tab

    The Container Tools tab contains tools for manipulating fire, smoke, and liquid.

  • Pyro FX tab

    Tools on the Pryo FX tab let you create simulated smoke and fire effects.

  • Solid tab

    Tools on the Solid tab let you create and modify solid objects.

  • Wires tab

    Tools on the Wires tab let you create flexible dynamic objects in the scene view.

  • Crowds tab

    The Crowds tab contains tools for creating crowds, crowd behaviors, as well as examples.

  • Drive Simulation tab

    Tools on the Drive Simulation tab let you manipulate dynamic objects in the scene view.

Technical