Computation of the flow in elliptical ducts

Abstract

Three-dimensional, incompressible laminar flow in ducts of uniform elliptic cross sections is considered. This work is related to the flow in engine inlets of contemporary air-breathing propulsion systems. Very often the entrance to such inlets is elongated in the horizontal direction. Transformation to a cylindrical-polar coordinate system is very inefficient as it concentrates many mesh points near the center where the flow is fairly uniform. Transformation to a rectangle does not lend itself easily to the prescription of small mesh distances near the solid wall. Coordinate transformation to an ellipse appears to offer certain advantages for such cases. Therefore we chose to study the flow in ducts with elliptical cross sections having various ratios between the major and minor axes. The equations were transformed to an orthogonal coordinate system. The solution domain was covered by an orthogonal finite difference mesh, staggered in all three coordinate directions.