Emission

In the Emission submodule, we will have the main options to configure our Fluid emitter.

The first thing we find is that we have 2 different options to emit. Count and Resolution.
Count: This method generates a "turbulent flow" emission. The particles are emitted randomly from the emitter faces, emitting during all the frames that the user indicates.
Resolution: This method generates a "Laminar flow" emission. The particles are emitted constantly in each frame. If for example we select a resolution of 100, our emitter will always emit 100 particles in each frame. This generates a much more controlled emission which is ideal for generating viscous fluids. It is important to note that this method only works correctly in single-sided emitters with 4 vertices, i.e., a plane.

Resolution Metohd, Laminar Flow

Count Method, Turbulent Flow

Next, we will have the Emission options. Here we can configure the quantity and size of the particles. The frame in which the emission starts, the frame in which it ends and the life of the particles. We can also configure different particle distribution options.

There are 2 IMPORTANT factors when configuring our fluid. The particle size must always be accompanied by the amount of particles. An incorrect particle size will cause our simulation to work incorrectly.

Let's see 2 examples of emission, with the same emitter, but one with 25,000 particles and another with 75,000 particles where the particle size is correct. We can see how both simulations work correctly.

Emission 25.000 particles

Emission 75.000 particles

It is very important that there is a balance between emitter size, particle number, emission duration and particle size. Here we can see 2 examples of a mismatch between particle number and particle size.

25k particle emitter with too large particle size. Emission becomes somewhat chaotic and uncontrolled.

25k particle emitter with too small particle size. Particles are too far apart because they are so small and do not allow a good simulation to be generated between them.

Soft

In the Soft panel, you can configure the "Geometry" type fluids to have a more controlled start. Normally when we have a Geometry fluid inside a container (for example a swimming pool), during the first frames, the particles adjust their position to start the simulation. This can be problematic in the first few frames, since we do not maintain the initial volume nor do we have a fluid that remains completely "calm" in the first few frames. With the Soft Start options, we can help to improve this problem.

By activating the SoftStart button, we will be able to configure up to which frame we want a "soft start". What will happen in the simulation, is that up to that frame, the Drag and Damp options will be increased so that the particles have a smoother behavior.

In addition, the "Interaction Radius" option will also be increased (which we will see later) so that the radius of interaction of the particles increases and maintains the volume of the geometry.

SofStart Off

SofStart On

Velocity

In the Velocity tab, we can configure the velocities of our fluid. As in the other tabs, we can convert this option into a "Local" configuration. In this way, we can for example have 3 emitters in the same group, with the same characteristics but different velocities in the fluid emission.

Fluid 1. The fluid has no velocity, gravity causes the particles to fall downward.

Fluid 2. The emitter has a velocity of 10m/s in the Z-axis, which causes the particles to be emitted upwards.

Fluid 3. The emitter has a velocity of 4.7m/s in the Z-axis and 4.3ms in the X-axis.

Viewport Display

In the Viewport Display tab, we can configure how we want to display the particles. By default the velocity of the particles is displayed, the closer the color is to red, the more velocity the particles have, and the closer they are to blue, the less velocity. We can also display the acceleration.

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