Houdini 18.5 Nodes Dynamics nodes

Labs Gas Expand from Temperature geometry node

Creates divergence from temperature change.

This microsolver can be used to augment a pyro network to expand or compress the fluid according to temperature change. This is done by storing the old temperature in an oldtemperature field that should be advected with the simulation.

It is important to setup the pyrosolver to process the oldtemperature field. Rather than performing advection internally to this solver, it is expected the field is added to the extra advection fields of the pyrosolver.

The Advanced::Advection::Extra Fields should have oldtemperature added.


Expansion from Temp

Changes in temperature will trigger expansion and compression of the field. This scales how much to apply that expansion.


Ambient Temp (K)

Used by divergence-from-temperature change to map the zero temperature.

Reference Temp (K)

Used by divergence-from-temperature change to map the one temperature.


Simple visualization options are included for the oldtemperature field. This is most useful to ensure it is properly advected.


These override which DOP fields will be used for each of the semantic operations.


Stores the current temperature and is used to detect the change in temperature.

Old Temperature

Stores the previous temperature. Will be re-initialized to the temperature value during this operation.


The field to add the desired volume-change to.

Use Timestep

Determines if the current solver timestep will be used to apply this node.

If set, the current timestep size will be multiplied by the scale and used for the time increment for this operation. Otherwise, the time scale will specify an absolute fictitious time to integrate by.

By disabling the link between the actual real time and the microsolver time, you can perform operations in a separate, fictitious, time.

Time Scale

The timestep used for this microsolver will be scaled by this amount. This allows one to achieve non-realistic effects, such as parts of the simulation operating at different speeds than other parts.

Similarly, it is useful if a solver needs to be evaluated independently of the main timestep.

Dynamics nodes