U-RANS Simulation of Mixed-Convection Around a Finite Wall-Mounted Heated Cylinder Cooled by Cross-Flow

Abstract

VALIDA experiments [1] were carried out within the framework of radioactive waste management to improve the understanding of mixed-convection flow and more particularly the interaction between a global cross-flow circulation and local natural convection effects around a vertical heated cylinder. The VALIDA loop implements a cylinder of 3.1 height to diameter ratio, mounted vertically in an insulated tunnel and cooled by a cross-flow air circulation. The air flow and the temperature fields on the cylinder and in the plume behind it have been numerically studied using Unsteady Reynolds Average Navier Stokes simulation (U-RANS) and compared to experimental data. The purpose of this paper is to present the results of a k-ω SST model on several test cases. The numerical tools used herein are Code_Saturne, EDF finite volume CFD code [2], and Syrthes, EDF finite element code for solid temperatures [9]. For the studied test-cases, Reynolds and Grashof numbers are characteristic of a sub-critical flow regime with laminar boundary layers around the cylinder and a turbulent wake. From the transient downstream air calculations, the plume behind the cylinder and its wall temperatures are analysed and compared to experimental data. The flow pattern strongly depends on the ratio of the buoyancy to the inertia force. Results show satisfactory qualitative and quantitative behaviour.