Numerical simulation of rarefied gas flow through nozzles and over submerged bodies
Abstract
A kinetic theory analysis is made of the rarefied gas flow through nozzles and over submerged bodies with arbitrary curvature. The Boltzmann integrodifferential equation simplified by a model collision integral is written in two different coordinate systems, and solved by means of finitedifference approximation coupled with the discreteordinate method. For internal flow, a Cartesian coordinate system is employed. The physical space is transformed by a general gridgeneration technique, and the velocity space is transformed to a polar coordinate system. For the case of external flow, an arbitrary orthogonal curvilinear coordinate system is used. Numerical codes are developed which can be applied to any complicated twodimensional internal or external geometry for the flow regimes from freemolecular to slip. Predictions are made for the case of parallel slots and are compared with existing literature data. Results for the cases of convergent or divergent slots and twodimensional nozzles with arbitrary contour at arbitrary Knudsen number are presented. Also, predictions are made for the external case of flow over a right circular cylinder in order to provide new results at transonic speed ranges where neither theoretical nor experimental data are available. The predicted drag on the cylinder is compared with existing literature data at low and high Mach numbers. For axisymmetric rarefied gas flow, the formulation is presented in which a cylindrical coordinate system with a general gridgeneration technique is employed to treat both internal and external flows.
 Publication:

Ph.D. Thesis
 Pub Date:
 1990
 Bibcode:
 1990PhDT........47C
 Keywords:

 Boltzmann Transport Equation;
 Finite Difference Theory;
 Gas Flow;
 Grid Generation (Mathematics);
 Kinetic Theory;
 Nozzle Flow;
 Rarefied Gas Dynamics;
 Submerged Bodies;
 Axisymmetric Flow;
 Cartesian Coordinates;
 Circular Cylinders;
 Mathematical Models;
 Polar Coordinates;
 Spherical Coordinates;
 Transonic Speed;
 Fluid Mechanics and Heat Transfer