particle advect

 

 

This node will advect particles along the voxel grid velocities and by the field gradient. For faster advection user can advect whole particle group at once.

 

 

[Inputs]

 

#Particle Stream - You can connect particles to this pin. However, advection will be much faster if whole particle group is advected at once by selecting the Particle Group.

 

Enabled - Enable or disable node evaluation.

 

Grid - Select available grid from the list. Any voxel simulation requires at least one of the nodes - FumeFX Simulation Ref or Initialize Grid node.

 

Particle Group - Select particle group for advection. This method is significantly faster than advecting particle by particle.

 

Update Type - There are several methods to move particle based on voxel grid velocities.

• Velocity : particle velocity will be replaced by the velocity from the grid.
• Force : velocity from the grid will be used as a force to accelerate particle in velocity direction.
• Position : particle position will be updated based on the grid velocity. This method conserves particle velocity.

 

Blend% - Using values lower than 100% will allow particles to keep their initial motion to some extent. At value of 100% particles will strictly follow grid velocities.

 

Use Mass - Enable this option if you want grid force to equally accelerate particle with different masses.

 

Delete Outside Grid ??? Enable this option to delete particle if advection takes it outside of the grid.

 

Advect by Velocity

Enabled - Enable advection by the grid velocities.

 

Velocity Scale - This value affects the rate at which particles will be advected.

 

Advect Type - Particle can be advected by using two different methods.

• Single Step : particle will be advected along the grid in one single step.
• Sub Steps : particle will be advected in multiple steps which similar to FumeFX Default and Conservative advections.

 

Advect Stride - Particle advection stride. This value is relative to the grid spacing where value of 1.0 means that advection stride is the same as grid spacing.

 

 

Advect by Field Gradient

In addition to the particle advection along the fluid velocity field, this node allows user to add another layer of advection along the field gradient.

 

Enabled - Enable advection by the field gradient.

 

Source Field - Choose the voxel grid field to compute the filed gradient.

 

Velocity Scale - Controls the influence of the gradient field on particle advection. Higher values increase the particle response to the gradient magnitude, causing them to accelerate more rapidly toward regions of higher field values. This results in narrower, more concentrated flow patterns. Lower values reduce the influence, leading to broader and slower particle movement.

 

Advect Type - Particle can be advected by using two different methods.

• Single Step : particle will be advected along the grid in one single step.
• Sub Steps : particle will be advected in multiple steps which similar to FumeFX Default and Conservative advections.

 

Advect Stride - Particle advection stride. This value is relative to the grid spacing where value of 1.0 means that advection stride is the same as grid spacing.

 

Advect by Field Gradient OFF	Velocity Scale 0.3	Velocity Scale 0.6	Velocity Scale 1.0

Example images show advected particles using different Velocity Scale values for Field Gradient Advection. Particles are rendered as Arnold points.