This Note suggests an improvement to the computational approach for axial turbulent flow in rod bundle subchannels. The turbulence anisotropy and its effects on the mean flow are numerically determined. The predictions require both fewer assumptions and empirical coefficients than the commonly used numerical methods. The physical model of turbulence proposed by Roco and Zarea in 1978 is used to express the Reynolds stresses in the momentum equations, in terms of the main flow kinetic energy multiplied by specific turbulence indices. All parameters, including the anisotropy factor, are predicted with a time efficient computer code written in FORTRAN IV. Galerkin's weighted residual finite element method is applied and the resulting system of algebraic equations is solved using Gaussian elimination with iterative improvement. The numerical scheme is applied for air flow in subchannels of a 3 × 6 rectangular array of rods and other rod arrangements. The results are in good agreement with the experiments using heated sensors, as well as with available analytical and experimental results. The approach applied here for the two-dimensional stream-cross case can be extended to three dimensional flow analysis.
