Foam - Foam Creation

Here you can define the conditions for the creation of foam particles based on various threshold parameters.

Bounded

By default, foam is created over the entire core fluid surface, but it is also possible to restrict this process to a given volume – a domain. When “Bounded” is set to “Yes”, a cube appears showing the domain's dimensions. This box can be scaled with the RealFlow's “Scale” tool (R key) or numerically with the “Scale” parameters under “Node”. A bounded foam domain is also needed when you want to simulate a scene via network with the help of IDOCs.

From splash

Foam can be created when splash particles enter or hit the core fluid's surface. Instead of using this completely automised mode, you can also create foam from the grid fluid domain or an image map (sequence). Please read through the introduction to the “Foam” emitter for more information about the interplay of the foam emitter's different creation modes.

@ radius threshold

When foam is generated from splashes this parameter determines the minimum radius of the splash particles that is able to produce foam. Splash particles with a radius below this value cannot contribute to foam anymore. When “From splash” is set to “No” this parameter is no longer accessible.

From domain

As an alternative, it is possible to create foam from the main fluid body instead of splash particles, but you can use both methods at the same time as well. With “Yes”, the associated parameters become unlocked and you will be able to define various threshold values to control the foam creation process and the areas of foam emission. These areas can be previewed – a description of how to activate this feature is described here.

@ emission rate

With this parameter you can directly define the number of emitted particles per second per cubic metre. It replaces the emitter's “Resolution” parameter.

@ angle threshold

This parameter takes the fluid surface's main direction of motion into account. The particles themselves also have an individual direction of motion caused by their velocity. RealFlow measures the angle between these two directions, and when the angle is between 0° and the given threshold splash particles will be added. The value is measured in degrees [deg].

@ curvature threshold

The core fluid's surface has a certain amount of “roundness”, also called curvature. Particle emission can also be controlled with this value.  This parameter is dimensionless and any value greater than or equal to 0 can be used. Higher settings decrease the number of particles, because a stronger curvature is needed for areas where foam is generated.

@ speed threshold

This value takes the grid fluid particles' speed into account. Particles with a speed smaller than the given value will be not be able to create foam. With 0.0, all particles can contribute to this process. Velocities are measured in metres per second [m/s].

@ vorticity threshold

Here, the grid fluid particles' vorticity is analysed. When the current vorticity is greater than the given value, the particle produces foam.

@ neighbors threshold

It is also possible to check against the number of neighbours of the current particle. Again, all particles with more neighbours than set here will be able to add foam.

@ position variation

Foam particles are always created within a certain distance around a source particle. With this parameter you can adjust this distance to avoid unwanted patterns. Higher values also increase the number of particles. This value uses metres [m].

Create particles from image...

Black and white images are another source of foam particles. This is a very convenient feature, because you can use digital photographs from real foam to get a convincing look. With this mode, the emitter adds one particle per white pixel.