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Initialize SlipstreamVX

This node initializes the data for the SlipstreamVX solver. It won't work properly without this node. This node initializes the vortex particles, the vorticity vectors and the radius of the vortices.

Usage

Plug this node "on Emit" of an Emit node. For example, it can be connected to the "Execute On Emit" of an Emit from Surface node.

Ports

VortexRate	The rate at which vortices are emitted.
Initial Vorticity	The average initial rotation vector of the vortices. Set this to zero if all directions are equally likely.
Vorticity Variance	The bigger the value, the more turbulent and random the flow will start out as.
Truly Random	If false, the random number generator repeats every frame.
Mean Radius	Mean radius of the vortices. A large radius makes a turbulent flow move together over large regions. Small values will create smaller scale features. This value should be chosen carefully with respect to the vortex rate. If you initialize too many vortices in a small space with a big radius, they will have the tendency to push each other apart. This can produce an interesting explosion effect.
Radius Variance	This is half the difference between small and large vortices. The maximum value should be less than the mean radius.

Simulate SlipstreamVX

This is the main simulator node that advects points through the wind field.

Usage

Plug this on an empty port of an ICE tree. Note that the ICE tree doesn't need to have a Simulate Particles node attached to it.

Ports

Enable	Enable/Disable the solver
Display Velocity Field	Display the velocity field created by the simulator.
Display Vortex Particles	Display the vortex particles in the flow
Enable Smooth Start	Enable the Smooth Start feature. This will gradually fade in newly created vortices, making the smoke less chaotic close to the emitter.
Smooth Start Duration	Duration of the smooth start, in seconds.
Age Vorticity	Specifies the minimum rotational speed for a vortex before it is deleted, in radians per second.
Reynolds Number	Specifies the Reynolds number for particles passing through the air.
Drag Multiplier	Multiplier for the wind resistance force on the particle.
Add Force	Adds a force to both vortex and smoke particles
Execute on Fluid	Executes on vortex particles
Obstacle In Name	Plug the Out Name of the profile you want to interact with the fluid and Vortex Shedding properties.
Collide with Obstacle	Takes particles from inside the colliding object. Enable this option if you see particles passing through objects.
Enable Vortex Shedding	Enables or disables obstructions. When enabled, it will cause the fluid to flow around the obstruction and generate turbulence behind it. When disabled, the fluid will flow through the obstruction. There are two aspects to this type of fluid / boundary interaction. The first is the laminar flow, which models the tendency of air to blow around an object. Turbulence is added to the laminar flow as the wind passes an object. The turbulence depends on speed, size of the object, etc. The parameters of Vortex Shedding are there to provide the desired effect. You can have turbulent flow happening right after contact with an obstacle, or just behind the object when the particles are moving away from the obstacle.
Detect Obstacle Distance	This defines the distance at which the fluid starts to move around the object. A higher value will tend to make fluid interact with the object farther away from the surface. You can see this as a general "scale" parameter of the fluid vs. boundary interaction model.
Turbulence	This defines how turbulent the flow will become when it passes the object
Turbulence Radius	Determines how large the turbulence features will be. This is similar to the mean radius parameter on Initialize SlipstreamVX.
Turbulence Speed	Determines how fast the vortices generated by the object will be spinning. Setting this to a negative number will reverse the direction of the turbulence.
Slip	Controls the surface friction of the object. This makes the wind close to an obstruction start to move the same speed as the obstruction. A value of 1 provides a frictionless surface that does not slow down the fluid. As this parameter approaches zero you get more friction. A value of zero will stop particles completely when they reach the object’s surface.
Cancel Incoming Velocity	Cancel out the velocity coming towards the object. This can be used to slow down the fluid near the object if it appears to be flowing too fast. The default of 0 will look good in most situations.
Random Position Vortices	Place random vorticity around the object. This is useful to model turbulent air around the object in addition to the turbulence generated directly in the flow.
Transition to Turbulent Flow	Defines the turbulent zone around the object. A negative number will allow the flow to become turbulent even when the fluid is coming towards the obstacle. A higher number will let turbulent region begin past the object.

Simulate SlipstreamVX (Simple)

This node has the same functionality as the Simulate SlipstreamVX node, but hides some of the advanced parameters. Please refer to the Simulate SlipstreamVX node for reference.

Delete Box

This tool deletes particles after they pass outside the limits of a box. This is useful to for keeping the simulation efficient by deleting particles that can no longer be seen by the camera.

It also allows vortices to be kept, since some particles (close to boundaries) may still be influenced by vortices that are outside the box. This prevents any popping when particles get detached from a deleted vortex.

Usage

Often this node is attached to the main execute node in an ICE cloud.

Ports

x min, y min, z min, x max, y max, z max	Allow the particle to exist just inside of these min x max limits.
Delete Points	Delete points outside the boundaries of the box
Keep Vortices	Won't allow the vortices to be deleted.
Execute Outside Box	Execute just on particles that are outside the box. You can, for example, choose to set a different color on particles outside the box.

Vortex Fan

This node accelerates the flow in one direction by periodically emitting two symmetrically positioned vortex particles. This can be used to create fans and jets.

Usage

One should connect this node to the "Execute on Fluid" port on the main "Simulate SlipstreamVX" node.

Ports

Vortex Rate	The rate at which vortices are emitted.
Position	The center of the fan. This is where the node will start emitting new vortex particles into the flow.
Acceleration	This is the direction we want to accelerate the flow.
Distance	A radial offset between the two particles from the original position parameter.
Radius	Radius of the vortices
Jitter	Adds a slight bit of randomness to the vortex positions. Useful if your flow looks too symmetrical.

Vortex Velocity From Curve

Allows one to control vortex creation from a curve. Very useful for animations that require fine control over the fluid's velocity.

Usage

One should connect this node to the "Execute on Fluid" port on the main "Simulate SlipstreamVX" node.

Ports

In Name Vortex Cloud	Plug in the Out Name of the vortex cloud. This node will set data on that cloud.
Geometry	The geometry used to perturb the flow. This node was designed to use Curves, but you can use any geometry you want.
Distance	The scalar field around the curve that will be detected when particles are close to it.
Force Multiplier	The amount of spinning added to the vortex
Variance	Randomize the spinning
Invert	Invert the force to flow outwards/inwards the geometry

Vortex Tornado

Allows one to create a tornado or whirlpool like effect.

Usage

One should connect this node to the "Execute on Fluid" port on the main "Simulate SlipstreamVX" node.

Ports

Emit Position	Emit position of the vortices to be inserted in the flow.
Spinning Axis	The rotation axis of the tornado force
Spinning Variance	Randomize the spinning axis
Radius	The radius of the tornado

Split Particles

This is used to cause particles to stretch and split. This can add a lot more detail to wispy smoke at the cost of a much higher particle count.

Usage

One usually connects this to the main "Execute" node on the ICE cloud.

Ports

Enable	Enable particles to split
Max Splitting	Max number of times one particle is allowed to split
Split Sensitivity	The sensitivity to flow deformation. This (with Max Splitting) is a key parameter to achieve high resolution smoke. Lower values result in more splitting.
Minimum Density	Minimum density allowed for a particle to split. This is useful for preventing particles from splitting once its density drops so low that it is hard to see.
Set Color On Split Particle	Sets a new color on particles resulting from splits. For debugging.
Color	The color split particles will display after split.
Shape	The shape of the split particle
Enable Density Gradient	Applies a gradient on the split. This will color particles based on their density. Particles that are very dense will maintain their color. Particles that "split" will walk this gradient
Gradient	The gradient color. Making this partially transparent will cause smoke to fade away as the particles split.
Jitter	Jitter the split particles, this is useful if you are looking to "fill in" a noisy particle cloud.
Distribution	How far the split particles will be from their parents. This attribute relates to the size of the particles.
Split Inheritance	Inherit the split count, or clear it for each split particle.

Initialize Split Particles

Allows for a particle to split during its lifetime.

Usage

Just connect this to the Execute on Emit of an emit node. If you want a particle to have the ability to split during its lifetime, it is necessary to initialize the attributes that are used to control the splitting upon the creation of that particle.

Ports

No ports are exposed.

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