Buoyancy driven turbulent flow and experimental validation at the VeMix test facility

Abstract

Buoyancy driven flow is often found in many engineering application such as the mixing process of fluids, which have different densities. The aim of this study is to simulate mixing of borated and unborated water, an issue which is relevant to the analysis of the safety of nuclear reactors. The degree of mixing of weakly and highly borated coolant is a critical issue with respect to reactivity of the reactor core. Therefore, a combined numerical and experimental study of buoyant mixing processes has been performed. As nuclear reactor geometries are complex, a vertical mixing (VeMix) test facility was used to validate the numerical models used with optical and surface wire mesh measurements. Good agreement was found between the physicality of the flow phenomena of the observed experiments and numerical calculations. Fourier analysis of the vortical oscillations in both the experiments and simulations also show good agreement for several flow conditions.