COMSOL Molecular Flow Module User's Guide

Introduction to Kinetic Gas Flow Simulation

This guide introduces the COMSOL Molecular Flow Module, an optional add-on package designed to enhance the COMSOL Multiphysics® modeling environment. It provides specialized physics interfaces for the accurate simulation of kinetic gas flows, particularly in rarefied conditions.

The module addresses the complexities of gas flows where molecular mean free paths become comparable to the flow geometry dimensions, a phenomenon critical in vacuum systems and high-altitude aerodynamics.

Key Features and Capabilities

The Molecular Flow Module offers two primary physics interfaces:

• Transitional Flow Interface: Suitable for modeling gas flows in the transitional regime (0.1 < Knudsen number < 10), utilizing a lattice Boltzmann method for isothermal flows.
• Free Molecular Flow Interface: Designed for flows where molecules collide more frequently with surfaces than with each other (Knudsen number > 10), employing an angular coefficient method.

The guide details the theoretical foundations, modeling approaches, and boundary conditions for these interfaces, enabling users to simulate a wide range of rarefied gas phenomena.

Resources and Support

Users can access extensive documentation, application examples, and technical support through COMSOL's online resources. For more information, visit the COMSOL website or the COMSOL Support Center.