3-D solution of flow in an infinite square array of circular tubes by using a boundary-fitted coordinate system (Q796373)

The paper presents the technique of boundary-fitted coordinates to solve thermo-dynamic flow problems. The coordinate transformations are found numerically as solution of a partial differential equation and may be applied to complex geometries. All pyhsical boundaries are transformed into constant coordinate lines; the boundary conditions can be specified on the grid points without interpolation. Numerical results are shown for the nuclear reactor application: an infinite square array of tubes of different pitch-to-diameter ratios. The developing velocity and temperature profiles are shown and compare well in the developed flow with analytical solutions. The numerical results were obtained with BODYFIT-FE, a three-dimensional steady-state/transient single-phase thermal-hydraulic finite difference computer code for rod-bundle applications. It solves the Navier-Stokes and energy equations by a cell-by-cell numerical procedure.