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This parameter is defined as mass per volume unit and is different for each substance. “Density” is only relevant for interacting fluids with different properties, e.g. water and oil, or water and foam. With single emitters, changes have no effect. The unit is kilograms per cubic metre. Avoid very small values close to 0, because they can lead to instabilities.
Int Pressure
“Int Pressure” simulates the forces between nearby particles and pushes them apart - this makes the fluid fill a greater volume. If “Int Pressure” and “Ext Pressure” are set to 0.0 the particles lose their fluid behaviour and they behave like “Dumb” particles.
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Substances with very high viscosity are honey, tar or syrup, for example. Fluids with low viscosity are alcohol, many solvents or liquid gases. The default value of 3.0 describes the viscosity of water. High settings (40-50 and higher) can lead to misbehaving particles.
Temperature
Here, the fluid's temperature is adjusted. In RealFlow, temperature is measured in Kelvin. The Kelvin scale is based on absolute zero point at roughly -273 °C, which represents 0 K; a temperature of 0 °C is 274 K.
Max Particles
Please enter a value to stop emission at a certain amount of particles. "Max particles" is based on the total amount of emitted particles. Let's say you have entered "50,000". If there are currently 1,000 particles in your scene, but you have already deleted 49,000 particles RealFlow will stop the emission. Here you can read how to use this parameter to stop particle emission: → "Quick Start Workflows - Stopping Particle Emission".