Nordita Astrophysics seminars

Interaction between a vertical turbulent jet and a thermocline

by Ekaterina Ezhova (KTH)

122:026 ()


We investigate the dynamics of a vertical turbulent jet in an unconfined stratified medium by means of well-resolved Large Eddy Simulations. Vertical turbulent jets serve as models of numerous flows both in nature and industry, including effluents from submerged wastewater outfall systems in the ocean, convective cloud flows in the atmosphere, pollutant discharge from industrial chimneys, subglacial discharge from submarine glaciers. The stratification considered is two layers of homogeneous fluids of different temperature separated by a relatively thin layer with a temperature jump - a thermocline. This configuration is a typical model of the upper thermocline layer in lakes, the pycnocline in the ocean as well as thermal inversions in the atmosphere. We consider two cases: when the thermocline thickness is small and on the order of the jet diameter at the thermocline entrance. We investigate mean jet penetration, stratified turbulent entrainment, jet oscillations and generation of internal waves and compare the results to the theoretical models and available experimental data. The results are applied to predict the dynamics of subglacial discharge and wastewater effluents in summer and winter conditions.