Here are all the new additions and updates!

Core

• Added 2 optional auxiliary fields. These are fields that can be sourced, advected, diffused, dissipated, and output similar to color but they are scalars instead of vectors.
• Height fields sourcing. The solver can now source height fields for collisions. You can plug the height fields into the source VDB input on the solver. You do not need to convert them to VDB as it will allow the "height" volume name to be a Houdini volume unlike other volume names. If you convert them to VDB yourself be careful of any zero value voxels as they will normally be pruned resulting in the bounds of your height field changing giving incorrect results.
• Added a variable number of in-flight buffers for VDB sourcing. If you are sourcing multiple VDBs at the same time it can now queue up more sourcing operations without needing to wait for previous ones to finish. This is defaulted to 4 meaning that if you source 4 or less VDBs there will be no delay in VDB sourcing. This speeds up VDB sourcing of multiple fields. It does use more host memory but not more GPU memory. This can be controlled in the advanced input settings.
• Fixed VDB validation during initialization so any VDB related issues will be caught at initialization time and not during run time.
• Fixed a bug where the solver sometimes output a false result on the frame before the start frame. It is now blank on all frames before the start frame.
• Color can now be downloaded as 16-bit when in 32-bit mode. All fields can now be downloaded as 16-bit when in 32-bit mode.

API & OS Support

• Added an “auto” option to the Compute API drop down menu. It will pick the best API based on the platform. This is on by default now.

Forces

• Faux advected wind. This simply advects the volume in the wind direction during the advection stage. Good if all you want is the sim to be shifting over instead of moving with velocity. Note it does not obey collisions at all.
• Added control field options to the ignition temperature control ramp.
• Fixed a bug where color diffusion was driving viscosity and vice versa.

Quality Of Life

• Solver now outputs a detail attribute for the used API and memory allocations per type. Separate detail attributes for shared, unified, and device memory. Good for keeping track of what happened with a render farm job.
• Better profiling timeline view. Better organization of time intervals. Will show the used API. Added reporting of memory usage.
• Version management improvements. Added an environment variable to the package json so users can query what the Axiom build number is from within Houdini. Added the build number to the HDA definition version metadata string. Also added the axiom_version detail attribute so you can know what build of Axiom created a particular cache.

Licensing