Fluid Sim

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Simulation/Fluid Sim

Performs a fluid simulation. ​

Description

The Fluid Sim box implements a real-time Navier-Stokes equation solver used to accurately simulate fluids such as smoke.

The Fluid Sim box has many parameters available to configure the simulation is many different ways. For a closer look at some of the possibilities of the FluidSim box, see RealMotion templates.

For detailed information about Fluid Simulation, see the nVidia page Chapter 38. Fast Fluid Dynamics Simulation on the GPU .

Inputs

Border 2D Texture Receives the boundary of the fluid simulation as a black and white texture. White pixels block the fluid simulation.
Density 2D Texture Receives the density texture to activate the fluid simulation.
Temp 2D Texture Receives the temperature texture.
Velocity 2D Texture Receives the velocity texture computed by the Velocity box.

Outputs

Border 2D Texture Outputs the border of the simulation in a texture.
Density 2D Texture Outputs the result of the simulation in a texture.
Pressure 2D Texture Outputs the pressure of the simulation in a texture.
Velocity 2D Texture Outputs the velocity of the simulation in a texture.

Parameters

Fluid

Dye

Replace Color Toggle Enables the replacement of the density by the dye color.
Color Float4 Determines the color of the dye injected by the Density input.
Density Multiplier Float Multiplies with the dye density injected by the Density input.
Clamp Input Density Toggle Activates the clamping of the density value between 0.0 and 1.0. When enabled, the fluid density is kept in the visible spectrum of a texture.
Texture Coordinate Reach Speed Float Used to generate texture coordinates as output instead of density. When set to zero, density is outputted. If set to 1.0 or near 1.0, texcoord is outputted. Otherwise, deformed texcoords is outputted.

World

Enable Input Pin: Border Toggle Activates the input pin Border. Inputs a black texture and enables the Blocking Outside Borders for a borderless simulation.
Blocking Outside Borders Toggle When enabled, the simulation is contained inside the simulation texture. When disabled, the fluid goes outside the borders.
Gravity Float4 Determines the global gravity applied to the simulation.
Velocity Multiplier Float Sets the multiplier applied to the Velocity input.
Velocity Maximum Float Sets the maximum velocity value permitted in the simulation. Used for stability control.

Behavior

Temperature Buoyancy

Temperature Buoyancy Enable Toggle Enables the buoyancy technique. The buoyancy simulates the convention currents caused by density and temperature change,
Combustible Dissipation Float Sets the damping applied to the combustible.
Temperature Dissipation Float Sets the damping applied to the temperature.

Fluid Behavior

Vorticity Dissipation Float Sets the damping applied to the vorticity.
Vorticity Confinement Enable Toggle Enables the vorticity confinement technique and keeps the rotations flows longer.
Vorticity Confinement Scale Float Sets the multiplier applied to the vorticity confinement technique used for increased vorticity simulation detail.
Viscosity Float Sets the fluid viscosity.
Dissipation Float Sets the damping applied to the density.
Velocity Dissipation Float Sets the damping applied to the velocity.

Paint

Paint Enable Toggle Enables the exponent to simulate drying paint.
Drying Exponent Float Sets the drying exponent applied when the paint mode is enabled. This technique increases the resistance in function of the inputted density and the time passed since the fluid creation.

Advanced

Simulation

Time Step Float Sets the simulation time steps. Used to control stability.
Simulation Passes Int Sets the number of fluid simulation passes executed in a single frame. Used for increased fluid speed.
BFECC Enable Toggle Enables back and forth error correction algorithms used for density and velocity advection steps. Enabling this function increases the sharpness and the noise of the simulation and reduces the performance.

Pressure

Pressure Optimizations Toggle Enables the pressure optimizations.
Pressure Passes Minimum Int Sets the minimal number of passes used to resolve for pressure. Increasing this value reduces performance but increases the pressure accuracy.
Pressure Passes Maximum Int Sets the maximal number of passes used to resolve for pressure. Better pressure accuracy is obtained by increasing this value. Better performance is obtained by lowering this value.

Format

Force Precision Toggle Allows to chooses the precision of the fluid simulation between16bits and 32bits.
Precision String Chooses the precision of the fluid simulation between16bits and 32bits. 32bits allows a more precision but is costly.

Canvas Settings

Set Resolution Toggle Allows the box to change the resolution of the outputted texture. Once enabled, this creates a new memory allocation for the texture created.
Resolution Mode String Sets the Resolution Mode. Canvas uses the project configuration settings, Custom uses local setting resolution not shared with other box and Project Aspect Ratio uses the project aspect ratio and proportionally scales the height and width. The parameter chooses the reference Canvas setting the resolution of the outputted texture.
Canvas 2D ResolutionRef Chooses the reference Canvas and sets the resolution of the outputted texture.
Maximum Resolution Int Sets the maximal resolution of the X-axis and calculates the resolution of the Y-axis based on the aspect ratio of the Content Canvas.
Lock Aspect Ratio Toggle Locks the Aspect Ratio for Custom resolution.
Aspect Ratio 2D ResolutionRef Chooses the reference Canvas for the aspect ratio.
Size XY Int2 Sets the size in pixels of the outputted texture.

See Also

Boxes related

Gradient, Threshold, Velocity, Format, Get Channel, Particle System 2D, Propagate Sim, Wave Sim, ​​

Version Information

Current documentation version: 2.1.4. ​ ​