Altair nanoFluidX 2021.2 Release Notes


New Extractor tool has been added.
Frame suite - Temporal frame
Temporal frame completes the frame suite set of tools introduced in 2021.1. Temporal frame allows for easy setup of water wading simulations where the car body is static and the road (and incoming water) are moving.
nFX[c] export Ensight Gold format
nFX[c] now supports Ensight Gold output format.

New Features

The Extractor tool is an advanced probe capability. Unlike the regular probe capability in nanoFluidX, the Extractor supplies an .stl mesh of arbitrary shape to the solver and all the desired diagnostics are then measured on this .stl mesh. If the .stl file is just a planar surface in the middle of the fluid flow, various pressures and mass flows can be measured using the Extractor tool. If the supplied .stl is actually that of the geometry, various forms of Fluid Contact Time can be measured as well as other physical variables directly on the mesh surface.
Frame suite - Temporal frame
Frame suite was specifically developed to tackle automotive water wading cases where there is a strong requirement to simulate the car entering the water, moving through a channel of a specified water depth, and exiting the water. Temporal frame (static frame) is complementing the previously introduced sliding frame (nanoFluidX 2021.1) by supporting a static car body with a moving floor. The frame suite makes such simulations significantly more computationally efficient and easier to set up.
nFX[c] export Ensight Gold format
nFX[c] now supports Ensight Gold output format to allow for more freedom in the choice of post-processing and for internal development support.
Polite simulation stop
When the ABORTFILE feature is used to stop a nanoFluidX simulation, recon files are now written upon the simulation stop. This is triggered by creating a SAVEABORTFILE in the running folder.
nFX[c] support for the frame feature post-processing
nFX[c] now accomodates for the moving domain (sliding frame) when in combination with a water wading simulation using a sliding frame feature.
Open MPI 4.0.6 and UCX 1.10.1
The latest available OpenMPI and UCX libraries are used to keep up to date with the rapidly developing hardware and maintain high performance.


Impose region definitions
Impose regions have been improved to allow for more flexibility in terms of possible options and scenarios. The PARALLELEPIPED shape (of which CUBOID is a special case) has been introduced. The new formulation of the impose regions are detailed in the User Guide. For backward compatibility, the old impose region definitions have been maintained, but the old definitions will be deprecated in the 2022 release of nanoFluidX.

Known Issues

  • Adhesion coefficient for the SINGLE_PHASE surface tension model needs to be calibrated against experimental results or visually estimated. Using the Tartakovsky single phase surface tension model is supposed to get around this by using a physical value of the surface tension.
  • Large negative pressures cannot be accurately handled by the current weakly compressible formulation without total particle volume preservation.