Study of a negatively buoyant jet of liquid metal in a density-stratified ambient

Abstract

Negatively buoyant jet of liquid metal (lead bismuth eutectic, LBE) at a low Prandtl number issued to a confined density-stratified ambient is investigated using large eddy simulation (LES). The Reynolds number and the densiometric Froude number of the jet are respectively Re = 8240, Fr = 29. The statistics demonstrate the features of the jet, such as the buoyancy effect and the presence of multiple shear layers. The misalignment between the turbulent heat flux and the temperature gradient implies that standard turbulence models are not suitable for such a flow.The low Prandtl number convection is compared with that of water at unity Prandtl number to investigate fluid similarity. The terminal penetration depth of the jet, mean velocity and temperature, and temperature fluctuations are analyzed. The velocity development of the LBE jet demonstrates the same behavior as that of the water jet, but the centerline variations of the mean temperature and the temperature fluctuations demonstrate the strong intensity of molecular diffusion in heat transport in LBE. The momentum and the thermal boundary layers at the side wall are compared with a similarity solution for laminar flow. The temperature distribution compares well with experimental data, demonstrating that the simulation returns satisfactory results.