Altair nanoFluidX 2020 Release Notes

nanoFluidX is a software to simulate single- and multi-phase flows based on the Lagrangian Particle Method "Smoothed Particle Hydrodynamics" (SPH) and is developed and maintained by Altair Engineering.

The purpose of this code is to simulate complex flows that are difficult or infeasible to handle using classical CFD approaches, such as Finite Volume Methods. The main advantages of SPH are the conservation of mass and momentum (linear and angular) in the absence of physical dissipation e.g. due to viscous shear effects and the exact advection of the particles. As a consequence, SPH is very powerful in dealing with free-surface flows as well as multi-phase flows with complex physical phenomena such as surface-tension or interfacial transport processes.

Highlights

  • Improved inlet region definitions: arbitrary orientation and location inlets are now available. Additionally, the inlets regions can also be assigned a motion (following a moving wall phase).
  • Outlet regions: outlet regions can now be defined at arbitrary locations within the domain.

New Features

Improved inlet region definitions
Arbitrary orientation and location inlets are now available. Additionally, the inlets regions can also be assigned a motion (following a moving wall phase).
Outlet regions
Outlet regions can now be defined at arbitrary locations within the domain.
nFX[c] runtime interpolation
nFX[c] can now be set up so that it executes the particle data interpolation in parallel with nanoFluidX. This implies that by the end of the nanoFluidX simulation, the interpolated data will also be available in full.
Velocity boundary condition
The velocity boundary condition can now be assigned to a static wall. When assigned to a fluid phase, the velocity boundary condition behaves like an initial velocity boundary condition.
Keychain validator
A tool for preliminary solver command check (checking the .cfg file).
nanoFluidX Monitor - nFX[m]
A tool aimed for more easily monitoring the nanoFluidX simulation during runtime. It allows for visualization of various parameters either in a terminal environment or a graphical window.

Enhancements

  • Mass flow planes are deprecated. The old method of using MASSFLOW phase type for measuring flow are out of service permanently. For obtaining mass flow values, please use the probe functionality.
  • nanoFluidX no longer supports CentOS 6 or its derivatives in accordance with the rest of the HyperWorks 2020 suite.
  • APD formulation has been improved to behave better in compression regions.
  • Large surface normal detection warning has been added when the solver detects an unusually large normal at a location. This can be critical for results quality when using Riemann interaction scheme.
  • Improved handling of shared storage in multi-node environment.
  • Probes are now aware of correction velocities introduced by transport velocity and APD.
  • Fixed an issue with cross-precision restarts.
  • Further Riemann interaction scheme improvements.
  • The debug script can now gather information from a run (intended for simulation debugging).

Known Issues

  • Surface tension coefficient for single phase flows requires tuning, as no universal single phase surface tension model exists.
  • Adhesion coefficient needs to be calibrated against experimental results or visually estimated.
  • Large negative pressures cannot be accurately handled by the current weakly compressible formulation without total particle volume preservation.