Nodes - Hybrido Secondaries (HySPH)

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Last updated: 27 May, 2014 by Anonymous
3 min read

One of the main characteristics of Hybrido is the combination of grid fluids with standard particle fluids to produce splashes and foam. The idea is to define various criteria to trigger the emission of fluid particles to add more details and a higher resolution. RealFlow's Hybrido secondary particle solver (HySPH) provides a broad range of particles for the creation of secondary particles. These secondary particle emitters are true all-rounders, because they can act independently from the grid fluid and become influenced by many daemons and are able to interact with objects. Dumb particles are surely the best choice, because they are very fast to compute, but you can also simulate them as liquid particle to enhance realism, e.g. in close-up shots. Splashes and foam can also be shaded and rendered separately from the core fluid to achieve white water, crests or sea foam.




To create more particles or particles in certain areas (for example on the surface of objects) RealFlow offers additional emitters like “Wet” or “Waterline”. In order to speed up a simulation, it also possible to use the “Splash & Foam” and “Wet & Foam” emitters. They combine the appropriate types within a single node.

Mist is treated separately, because it does not emit particles. Mist is a variable density field to represent hazy or foggy areas with droplets too small to visualize them as individual particles.

Concepts

The great advantage of the HySPH emitters is flexibility. Secondary particle emitters are restricted to a certain space, also called a domain. This concept allows you to create defined zones where secondary particle are created. Another huge advantage with domains is that they can be calculated independently and therefore it is possible to distribute the simulation of splashes or foam over multiple computers using IDOCs (Independent Domain of Computation). You can access core fluid particles from several computers and each of them carries out a certain number of splash domains, for example. As long as the domains are calculated on different machines, they do not interact with each other, but in most cases that is not really necessary. Of course, this workflow requires an appropriate number of RealFlow licenses. For more information please contact Next Limit's sales team.

The emitters can be placed anywhere within the higher-ranking grid fluid and there is no need to make them available to the entire scene. For example, it is possible to restrict a splash emitter to a rocky coast line, where you would expect impressive splashes. Another idea would be to place an emitter only around an island or bound it to a moving ship for creating foam along the body. You can use as many emitters as you want and control their resolution independently from each other. This allows you to adjust the accuracy and the number of particles based on the viewer’s distance: nearer parts will use high-resolution emitters, while distant splashes consist of just a few hundred particles.

Another sophisticated feature is the user’s freedom to decide whether the particles should be generated while simulating the core fluid or create them in a post process from a cached Hybrido sequence. With small scenes it is surely not a problem to do all this within a single scene, but with multiple secondary particles from different emitter sources, it is the right time to think about network simulations with RealFlow's IDOCs.

Particles

Splash and foam particles act like standard particles and they share some of the physical properties of their counterparts. They can also be influenced by most of RealFlow daemons and react with each other. Nevertheless, there are few differences – mainly to accelerate a simulation:

  • The default type is “Dumb”.
  • You can only choose between “Dumb” and “Liquid” particle types.
  • Hybrido secondary particle emitters use a reduced set of parameters.
  • Currently, HySPH particles cannot contribute to wetmaps. These maps can only be created from "real" SPH emitters.

Daemons

Please take a look at the table under "Daemons - Compatibility Table". There you will find a complete list with the daemons which can be used with HySPH particles.