turbulence_influence

The turbulence influence applies a curl noise acceleration, which is useful for effects like air turbulence. A nice feature of the curl noise is that the resulting velocities are incompressible, like an air flow, which results in more natural particle smoke simulations. In such cases higher drag values will help the particles to more closely follow the curl noise flow instead of building up velocity over time.

To use this node, plug its output into the influences input of a simulate node like simulate_aero, simulate_particles, or simulate_mpm.

Inputs

influence

One may optionally connect an influence field out_influence into this port. For example a mask_influence node could be connected to mask the effect of this influence. Any number of influence fields may be added to the daisy chain to build a complex field.

enable

Turn off to disable the effect. Disabling makes it a pass through node. Note that any other influence fields connected to the influence input port will still be active when this is disabled.

turbulence

The magnitude of the acceleration to apply to the simulation velocity.

You can connect a float, ScalarField, float3, or VectorField. VectorField and float3 values modulate the effect differently in each axis.

frequency

This controls the size of the noise. Higher values result in smaller vortices. One may wish in some simulations to have both large scale and small scale vortices, in which case one could chain together more than one turbulence_influence, each with different frequencies. Note that lower frequency values also generally require higher turbulence values.

change_rate

This controls how fast the curl noise evolves over time. If it is zero then the turbulence will have fixed vortices that do not change over time.

drag

This will dampen the current simulation velocities, resulting in less velocity buildup over time. High values of drag will fully replace simulation velocity with the turbulence acceleration, instead of continually adding in the acceleration. This is useful for simulating smoke particles being pushed by a turbulent wind. You can connect a ScalarField to vary the effect over space.

Outputs

out_influence

An output influence object that one can connect to simulation nodes or other influence nodes.