Authors

An attempt has been made to apply the direct numerical simulation (DNS) to a fully-developed single-phase turbulent flow analysis for an eccentric annulus channel configuration. The objective of this investigation is focused on the heterogeneity and local laminarization phenomena similar to those that prevail in the tight lattice rod bundle configurations. The DNS algorithm adopted here is based on the finite difference method being extended to the boundary-fitted coordinate system, verified for a number of numerical benchmarks and turbulent flows in flow channels of simple geometry, and can concentrate grids effi-ciently near the narrow gap boundary region. First a comparison between the DNS calculation and the numerical benchmark results by the spectral method has been made for flows in concentric annuli to demonstrate the accuracy of the DNS. Then the computations have been extended to a flow with the friction Reynolds number Reτ = 770 in an eccentric annuli, first to get qualitative insights into the turbulent structure in reference to the experimental data available with higher friction Reynolds number Reτ = 1,440, and then to see the local laminarization near the narrow gap region