FLOW NUMERICAL ANALYSIS METHOD FOR SETTING BOUNDARY CONDITION OF UNRAMIFIED AND NON-ORTHOGONAL STRUCTURAL GRID AND USING ITERATIVE COMPUTATION

摘要

PPROBLEM TO BE SOLVED: To set a boundary condition in the case where a differential coefficient in a direction perpendicular to a boundary is not 0 when performing iterative computation using an unramified and non-orthogonal structural grid, so that numerical calculation doesn't become unstable and a solution of high precision can be obtained. PSOLUTION: With respect to a boundary condition of a calculation cell in a part wherein a differential coefficient in a direction perpendicular to the boundary is not 0, a cell in a position symmetrical to the calculation cell with the boundary as the axis is supposed on the outside of a v calculation area, and a contravariant velocity of the supposed calculation cell is defined using a coordinate conversion coefficient for conversion between a coordinate system and a Cartesian coordinate system, and the contravariant velocity is used to define a symmetrical boundary condition to be given, and when an equation of motion is solved by an iterative computation method, a coordinate conversion coefficient of the calculation area is used to express a coordinate conversion coefficient about the calculation cell supposed on the outside of the calculation area, and a physical velocity of Cartesian coordinates obtained by reflecting the boundary condition in previous iterative calculation and the boundary condition are used to calculate an unknown in current iterative calculation. PCOPYRIGHT: (C)2011,JPO&INPIT