NMEM(Neutral Momentum Equation Module) computes spatial distribution of density and pressure of each neutral species by continuum model.

Description of method

NMEM is a module to compute flow field of neutral gas without electric charge. We assumed that the neutral gas would be regarded as ideal gas and continuum approximation would be realized. Then this module computes pressure, density and flow field of each species by solving mass conservation law ( continuity equation) and momentum conservation law ( Navier-Stokes equation). At this time, we assumed temperature distribution would be constant for each species. So, energy conservation law was not solved. This module is discretized using finite volume method. Computational algorithm is fully implicit method by expanding SIMPLE method for non steady state and compressible fluid.

Input data

• Specify computational domain, flow-in, flow-out and obstacles defined by two-dimen sional rectangular mesh system in Cartesian or cylindrical (axial symmetry model) coordinates.
• Specify the following boundary conditions for flow-in and flow-out for each species.
  • Fixed flow velocity
  • Fixed mass flux
  • Fixed pressure
  • Free flow-in/flow-out
• Specify the following boundary conditions on a solid material for each species.
  • Free-slip
  • Non-slip
• Specify the temperature and initial pressure for each species.

Output data

• Spatial distributions of density, pressure and flow-velocity for each species.

Example

• Flow field for two kind of neutral gas
• Flow field across a square pole