Abstract
An Immersed Boundary Method (IBM) has been incorporated in a finite-difference code to solve the three-dimensional incompressible fluid flow using the boundary-fitted general curvilinear coordinate system. IBM has been developed for solving flows over complex boundary shapes on rectangular grids. In the present work it has been extended to be used in the boundary fitted coordinate system in order to represent complex objects on curving boundaries, such as undulating terrain with buildings and other objects. Basic verification study has been conducted by computing laminar flows over a model terrain and model rectangular objects to verify merits and efficiency of such a procedure compared with conventional methods. It is found that the IBM technique incorporated in a sigma-coordinate system in which the first coordinate follows the boundary representing the terrain and the second coordinate axis is taken in the straight vertical direction is most appropriate in both accuracy and efficiency, and is suited for calculating flow over topography with objects of various shapes.
