A 3-D solution of flow in an infinite square array of circular tubes by using boundary-fitted coordinate system

Heat transfer and fluid flow over circular tubes have wide applications in the design of heat exchangers and nuclear reactors. However, it is often difficult to accurately calculate the detailed velocity and temperature distributions of the flow because of the complex geometry involved in the analysis, and a lack of an appropriate coordinate system for the analysis. Boundary conditions on the surfaces of the tubes are often interpolated. This interpolation process introduces inaccuracy. To overcome this difficulty, the technique of the boundary-fitted coordinate system was used. In this technique, all the physical boundaries are transformed into constant coordinate lines in the transformed coordinates. Therefore, the boundary conditions can be specified on the grid points without interpolation.