The generation of foam particles is closely linked to the grid splash emitter, but it is also possible to create them directly from the domain. In this mode, the creation process is very similar to the creation of splashes and you will use the same parameters: curvature, speed etc. An interesting feature is that both modes, “From splash” and “From domain” can coexist and be used simultaneously. A third option is to use photos from real foam as a template to add new particles.
The "Foam" emitter in action.
Let's take a closer look at the “From splash” mode:
When splash particles hit the surface of the core fluid they are destroyed, but at this moment they are capable of producing foam. The amount of foam particles is determined based on the number of dying splashes. The only way to control the number of foam particles is to increase “@ radius threshold”. Splash particles with a radius smaller than the given threshold cannot contribute to the fluid's foam.
With “From domain”, the creation process is completely different, because here you have full control and the trigger is not an event, but a range of threshold parameters. These parameters are based on the underlying core fluid's surface structure and some physical properties. The analogy of these parameters with the “Splash” emitter is, as mentioned above, no coincidence. This is also the reason, why the emission areas of foam can be previewed with the domain's “Property” option in the “Display” panel. There you will find values which have exactly the same names and meanings as the parameters of the “Foam” emitter. Please visit this page for a detailed description of how to use Hybrido's splash and foam preview.
Like “Splash”, the “Foam” emitter has its own domain represented by a box when “Bounded” is set to “Yes”. Foam must be linked to a domain in order to become created and any splash, attached to the domain, will generate foam – as long as “From splash” is set to “Yes”. Foam particles are only generated within this domain, but can escape from it. Multiple foam domains can be added and placed inside the grid fluid domain, and computed on different machines at the same time with the help of RealFlow's IDOCs. Foam particles cannot interact with daemons, because they are controlled directly by the HyFLIP solver. Please also bear in mind that they are always simulated as “Dumb” particles. Hence the “Foam” emitter has a drastically reduced “Particles” panel and all relevant physical properties are calculated internally.
The “Calculate particles from image...” uses already existing maps to emit foam. In this case, the amount of foam is controlled by the “Splash” emitter's “Foam strength” parameter. The image-based creation of foam can either be exclusively used or in combination with “From splash” and “From domain”.