Grid Types Processed

 

All three PHOENICS grid types can be processed by the interface program. Coordinates for regular Cartesian and Polar grids are calculated from the cell face values in the PHI(DA) file. BFC grid coordinates are read from the XYZ(DA) file.

In FEMVIEW a grid is referred to as a mesh and cells are called elements. In the process of translation the cell corners become FEMVIEW nodes.

Nodes and elements are numbered, and these numbers are generated by the interface. The equation used to generate element numbers is:-

Element Number = J + {I-1}*{NJ} + {K-1}*{NI*NJ}

where I, J and K are the locations of the cells in the grid. NJ is the total number of cells along J, and NI is the total number of cells along I. The equation for node numbering is similar but, in this case, the I, J, and K parameters, refer to the cell corners. However, as the I, J, K definition of a grid is available within FEMVIEW, it is unlikely that the user will often want to access the grid in terms of node and element numbers, but will prefer to use I, J, K values instead. If the grid is multiblock this will be repeated for each block with the addition of a block offset.

The element type in FEMVIEW to which all cells in a 3D model are mapped is the 8 noded brick element (HE8); for 2D models 4 noded quadrilateral elements (QU4) are used. Cells at the centre of polar coordinate models are mapped to degenerate HE8 elements, and will resemble PE6 elements.