A general synthetic iterative solver for axisymmetric rarefied gas and electrostatic charged-particle flows

An axisymmetric general synthetic iterative scheme (AxiGSIS) is proposed to simulate rarefied gas flows and charged particle transport under prescribed electrostatic fields.

This solver adopts a finite-volume discrete velocity method defined over the two-dimensional axisymmetric meridian plane paired with a three dimensional molecular velocity space.

Under the GSIS framework, the kinetic solver computes nonequilibrium stress and heat flux, which are subsequently imported as corrective source terms into the macroscopic synthetic system.

Fast iterative updates of low order flow primitive variables are performed on this macroscopic system, whose corrected flow fields are then fed back to the kinetic solver.

This bidirectional coupling enables rapid propagation of macroscopic information and substantially accelerates steady state convergence, particularly in near continuum flow regimes.

Four benchmark flows are examined: the Taylor Couette flow, neutral nozzle expansion flow, charged particle flow past an electrostatic sphere, and electrostatically accelerated charged-particle nozzle flow.

Results show that AxiGSIS reproduces the reference kinetic solutions and accurately captures axisymmetric flow physics and charged-particle responses to prescribed electrostatic fields.

Utilizing fewer spatial cells and iteration steps, AxiGSIS substantially cuts computational overhead relative to conventional kinetic iterations, particularly for low and moderate Knudsen number flows.