Application of LES with near wall model in nuclear plant thermal hydraulics

Takata, Takashi*; Yamaguchi, Akira*; Tanaka, Masaaki  ; Ohshima, Hiroyuki

A Large Eddy Simulation (LES) with a simple Sub-Grid Scale (SGS) model and a Near Wall Model (NWM) is one of the simplest ways to overcome the heavy computational cost. In the present paper, two kinds of benchmark analyses have been carried out in order to investigate an applicability of the simple LES with NWM to an engineering problem concerning with a nuclear plant thermal hydraulics; one is the temperature mixing in the parallel triple-jets and the other is the isothermal turbulent flow under a rod bundle configuration. In the analyses, the standard Smagorinsky model is chosen as a SGS model using a second order central differential scheme. As the NWM, a wall function and a boundary layer approximation are implemented. As a result of the benchmark analyses, it is demonstrated that one can investigate a temperature fluctuation which causes a thermal striping phenomenon and a flow pulsation in a rod bundle configuration with the present LES with NWM.