A modified relaxation time Monte Carlo method with a multiple translational temperature model for micronozzle gas flows

Gas flow in a micronozzle is usually in a continuum-transition region. The relaxation time Monte Carlo (RTMC) method was modified by using a multiple translational temperature (MTT) model and a simplified form of the generalized relaxation time related to the macrovelocity and the local Knudsen number in the BGK model equation to simulate micronozzle gas flows. The numerical results predicted by using modified RTMC with the MTT model are in good agreement with the experimental data and numerical results of the direct simulation Monte Carlo method and 2D Navier–Stokes (N–S) equations. The physical mechanism of the microscale effect is discussed. The first sonic point is not at the throat of the micronozzle here, because the gas quasi-one-dimensional steady adiabatic assumption fails, due to the significance of increasing viscous dissipation