Altair ultraFluidX 2023 Release Notes

New Features

New wall model coupling method and model
ultraFluidX is pleased to introduce a new wall model coupling method and corresponding wall model formulation in the 2023 release. The new adaptive two-way coupling imposes the right near wall slope of velocity as well as the right near-wall eddy viscosity based on information collected in the near wall region and the chosen law of the wall. The updated coupling used in conjunction with the generalized law of the wall (GLW) wall function has been shown to give promising results and is now the default for ultraFluidX and is implemented as default in the Virtual Wind Tunnel (VWT). It should be noted, that when applying adaptive two way, the bounding walls (excluding inlet and outlet) are automatically defined as link-based boundary condition.
H3D export
ultraFluidX 2023 introduces a new option to extend the functionality of files written out by ultraFluidX. In addition to EnSight Gold, results can now be exported in the H3D file format. By having this output available, users have more options for post-processing. Results from all types of visual output can be written out in the new format.
Generate monopolar white noise
ultraFluidX 2023 extends the acoustic source available in ultraFluidX 2023 by introducing a white noise acoustic source. This acoustic source generates a random pressure fluctuation within two times the amplitude specified by the user. The user has the possibility to keep the random fluctuations constant for a certain number of iterations.


Option to merge a subset of output files
ultraFluidX 2023 introduces a new option to request to merge only a subset of output files, rather than merging all of the files available. This feature is available for all the output subcategories available in ultraFluidX. This allows a user to, for example, only merge a partial surface, thereby reducing the overall diskspace of the merged files.
Ability to export density
ultraFluidX 2023 introduces the ability to export density (instantaneous as well as time and window averaged) for all categories of exported data.
Modify the precedence of slip boundary condition
With the updated coupling in ultraFluidX and subsequently updated link-based boundary condition it was important to adjust the precedence to ensure the correct boundary condition is applied along the inlet and outlet surfaces. Slip boundary condition now takes precedence over rotating, moving and static boundary conditions.

Resolved Issues

  • Unphysical pressure fluctuations at porous media and solid surface interface have been removed. Isotropic porous media now can safely be used with wall contact and large values of viscous resistance, for example, to model insulation material for acoustic absorption.
  • When merging results previously using ultraFluidX -merge uFX_output.sos the merge would fail and only be successful when called as ultraFluidX -merge ./uFX_output.sos. This has been fixed and now merging will be successful with both ultraFluidX -merge uFX_output.sos and ultraFluidX -merge ./uFX_output.sos options.
  • It was observed that temporally averaged surface quantities within an OSM region show zeros only, while volume outputs were not affected. The functionality was restored, and now temporally averaged quantities are present in OSM regions on surfaces.
  • A reproducibility issue caused by the turbulence generators has been fixed. Results are now meeting reproducibility requirements again.