What's New

View new features for ultraFluidX 2023.1.

Altair ultraFluidX 2023.1 Release Notes

New Features

Virtual Fan: ultraFluidX 2023.1 introduces a new virtual fan model. The model allows you to replace a resolved rotating fan geometry by momentum source terms based on a user-defined P-Q curve.; Specifically, you can define a volumetric source region and four coefficients that describe a third-order polynomial reconstruction of the fan’s P-Q curve. The source term applied in this zone is based on an actuator disk model and will represent the induced shift in axial flow velocity. The feature can optionally also update the tangential flow velocity consistently.; The volumetric source regions can have an arbitrary shape as long as they are closed volumes. For internal/HVAC cases, the source zones should be fitted to the cross section of the ducts and the tangential components of the model should be deactivated. To capture local flow phenomena of rotating fans more accurately, the use of disk-shaped source regions and the optional tangential components are recommended.
Far-Field Noise Predictions (Beta): For certain aeroacoustics applications, such as fan noise, HVAC noise and train community noise, you need to evaluate flow-induced noise levels at microphones located far-away from the turbulent regions simulated in ultraFluidX. To support this requirement, sufficient resolution must be added between the source regions and the microphones to accurately propagate acoustic waves with a minimum of dissipation. In some cases, this additional resolution leads to a significant increase of the simulation size and associated computational time. To overcome this limitation, ultraFluidX 2023.1 introduces a far-field noise solution based on the resolution of the Ffowcs Williams - Hawkings (FW-H) analogy. The solution consists in reconstructing the far-field noise levels at any distance from the source regions by processing transient flow information recorded in the source regions. The current capability uses input data recorded on non-rotating physical surfaces (partial surface output) or fictitious surfaces (monitoring surface output) to support the solid and porous FW-H formulations, respectively. This beta version supports an initial implementation submitted as a post-processing step after the ultraFluidX simulation.

Enhancements

Surface Roughness Parameter for Wall Model: ultraFluidX 2023.1 offers to approximate the effect of surface roughness for wheels and belts via additional terms in the wall model.; You can indicate a characteristic roughness height for each wheel/belt instance, which serves to determine a correction term during the calculation of the wall shear stress.
Note: This option is available for the Generalized Law of the Wall (GLW) wall function only.

Resolved Issues

Incorrect merge of H3D files for cases with multiple overset mesh regions into a single overset region has been fixed.

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.

Enhancements

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.