Mixing Depth of a Submerged, Horizontally Injected Buoyant Jet

Abstract

Tests in the laboratory were conducted to determine the effective mixing depth of turbulent buoyant fluid injected horizontally into an initially unstratified environment through a radial, deeply submerged diffuser. The diffuser was moved slowly during the experiments, at a rate much smaller than the entrainment and mixing process. The effective mixing depth is defined as the relative position between the initial injector level and the lowest position of the resulting mixed layer over which the injected fluid is deposited. Results have applications to discharge of contaminants and heat into large reservoirs (sewage disposal, power plants, OTEC systems) and establishment of a stratified region as is required for operation of salt gradient solar ponds. A functional dependence between mixing depth, scaled by the injector slot size, and injector Froude number was found. Dependence on submergence was not found for the large submergence values tested; dependence on diffuser radius was not investigated. The laboratory data compare well with results obtained in a reservoir of 3355 m2 surface area and indicate a strong dependence of effective mixing depth on the Froude number.