Abstract: Method for forming a fixed geometric grid for a fluid dynamics system multi-cell computer model, the system having one or more surfaces, includes representing the system surfaces by an array of contiguous polygons. The method also includes creating a single model cell that encompasses the entire system and assigning all the surface polygons to the single model cell. The method further includes subdividing at least the portion of the single model cell encompassing the surface polygon array, including subdividing all intersected assigned polygons, using one or more subdividing planes. The method still further includes reassigning the surface polygons to respective subdivided cells resulting from the subdividing step, identifying those subdivided cells having two or more surface polygons from a common system surface, and calculating effective common boundary areas and normal vectors for those cells. The method also includes treating “split” cells and “sliver” cells.

Abstract: Method for treating a moving surface during a transient condition in a computational fluid dynamics system multi-cell computer model, the model having a fixed underlying geometric grid, includes identifying cells in the grid adjacent the moving surface at the beginning of a transient time step and identifying beginning adjacent cell boundaries formed in the grid by the moving surface. The method also includes computing effective thermophysical value fluxes through the beginning cell boundaries in accordance with the sense of the movement of the moving surface relative to the beginning adjacent cells. The method further includes solving transport equations for all the cells to determine cell thermophysical values at the end of the time step, using the computed effective fluxes and reforming the grid to comply with the moving surface at the end of the time step. Apparatus includes a digital computer programmed to carry out the above method.

Abstract: Method and apparatus are disclosed for implementing a geometric multi-cell system dynamics model having an embedded grid, the embedded grid having cells with a finer grid size relative to the grid size of other cells. The apparatus includes a digital computer having a computational fluid dynamics model program stored therein, the program having software for iteratively solving transport equations for thermophysical values for the embedded cells and the other cells, and for solving residual equations for the values for each cell using a multi-grid computation method. The program also has other software for computationally manipulating the embedded grid cells to provide composite cells of the same grid size as the other cells and having averaged residual thermophysical values, for allowing the multi-grid computation method to operate on the embedded grid cells.