A grid fluid emitter always needs an object applied to be able to generate particles. The following settings are used to establish this connection and define the emitter’s mode of creating particles.
Object
This setting defines the object used for creating the particles. You can attach a new object at any time, but it is not possible to bind more than one object to an emitter. If you want to use more objects you have to add the appropriate number of emitters. We recommend removing the attached object from the "Relationship Editor", because the emitter object is not meant to interact with other nodes. In case you forgot to disconnect the emitter object, RealFlow will not consider it for the simulation anyway, but you will receive a warning in the “Messages” window. The attached object can have any shape and it is also possible to use imported objects.
Stream
By default, particles are created inside the volume of the attached object and then released. With this parameter it is possible to switch on a continuous particle stream, similar to RealFlow’s standard emitters. To make the emitter create particles with “Stream” turned on, “Initial speed” can even be 0.0. In such a case, the particles’ velocity is a result of the scene’s daemon forces.
Initial speed
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@ speed
This parameter indicates the magnitude of the initial velocity of the fluid and is measured in metres per second [m/s]. The direction of the initial velocity can be controlled by simply rotating the emitter node in the viewport. An arrow in the centre of the emitter’s symbol indicates the direction.
@ angle variation
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@ speed variation
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Surface particle sampling
The Hybrido fluid's surface plays a very important role with Hybrido simulations, because it is responsible for the creation of the secondary effects as well as the quality of the mesh. The particles inside the cells also contribute to these features. With this parameter it is possible to adjust the number of surface particles within the given "Surface bandwidth" – independent from the main body of fluid. The total number of particles per cell is calculated with the following formula:
Number of particles per cell = Surface particle sampling 3
Surface bandwidth
Within the adjusted bandwidth (given in metres), the “Surface particle sampling” value will be applied to the particles. Below this distance, the “Core particle sampling” parameter is used. "Surface bandwidth" can be seen as the surface's "thickness".
Core particle sampling
Analogue to “Surface particle sampling” the main fluid body can be adjusted as well. With this parameter you determine the number of particles of a cell outside the “Surface bandwidth”. These particles are considered "core" particles. The formula is exactly the same as above:
Number of particles per cell = Core particle sampling 3
Jittering
RealFlow spreads the particles of the emitter equally over the entire grid, respectively over the attached object’s volume. This results in a regular pattern and in some cases to slightly uniform simulations. To avoid this, it is possible to apply a random value to displace the particles from their original positions. The value determines the maximum distance from the original position without colliding with a neighbour particle. You can choose from values between 0 and 1 and, of course, “Jittering” leads to completely different simulations.
@ seed
This value is connected to “Jittering” and produces a random number for initializing the particles’ displacement.