Altair nanoFluidX 2021.1 Release Notes


Porous Media
nanoFluidX is now capable of simulating volume-averaged iso- or anisotropic moving porous media using the Darcy-Forchheimer model. The implementation is done through the Regions feature, such that you can define cuboid, cylindrical or spherical porous regions with defined porosity in any direction. Each prescribed region can follow a prescribed motion of one of the moving bodies in the simulation.
Frame Suite
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. While such simulations were in principle always theoretically possible in nanoFluidX, the frame suite makes such simulations significantly more computationally efficient.
Car Motion (Double Roller)
Complex motion in nanoFluidX was always an option, but the double roller motion specifically targets easy car motion definition. A simplified set of parameters will allow for correct vehicle behavior, including wheel rotation, translation and car body following the wheels and behaving accordingly. The motion is currently “stiff” as it does not include any suspension modeling.
CUDA 11.1.1 and OpenMPI 4.0.5 (New)
Using the latest available CUDA and OpenMPI libraries to keep up to date with the rapidly developing hardware and maintain nanoFluidX’s signature high performance.


Inlet Flowrate Definition
The inlet regions can now accept input in the value of mass or volume flow, not just velocity. The user can now input desired mass of volume flow rate in units of [kg/s] or [m3/s].
ParaView Export
nanoFluidX and nFX[c] now both export Paraview state files which will load all the output data into Paraview. The feature requires using SimLab 2021.1 and will have full compatibility with the coming Paraview 5.9.1 version. Utilization of this feature with Paraview 5.9 or earlier will be limited as the motion visualization will be compromised. However, starting with 5.9.1, Paraview will fully support all nanoFluidX motions.
nFX[c] Archiving
Upon request, nFX[c] will now automatically compress its output data to .tar or .tar.gz format.

Known Issues

  • Adhesion coefficient for the SINGLE_PHASE surface tension model needs to be calibrated against experimental results or visually estimated using the Tartakovsky method.
  • Large negative pressures cannot be accurately handled by the current weakly compressible formulation without total particle volume preservation.

Resolved Issues

  • Corrected calculation of the center of mass and its velocity when sub-phasing was turned on.
  • Corrected a bug regarding the polynomial temperature-viscosity model where some of the coefficients were not active.