Evolution of convection and turbulent jets in stratified low aspect ratio containers.

摘要

An experimental study was conduted to investigate the evolution of a density (solute) stratified fluid in an confined environment under the action of a destabilising heat flux and a turbulent neutrally buoyant jet. In the former case, the heat flux was supplied either from below or from below and the sides. In the bottom heating case, the growth laws for the mixed layer was predicted for the low asppect ratio (width / height) case, and was evaluted experimentally. The velocity and length scales of side-wall affected mixed layers were also inferred from the growth measurement, and were experimentaly verified. When heat was supplied from the sides, a series of double-diffusive layers are formed almost simutlaneously within the bulk of the fluid , and the evolution of these layers were much different from the bottom layers, which was affected by the wall effects. Parameterizations were presented based on experimental results for the thickness of these layers, and detailed structure of convection in these layers was also identified. In a separate but related study, the interaction of a density interface with a jet emanating from the top of a two layer fluid contained in a low overall aspect ratio container was studied, and the depth to which the interface advances due to initial, intense mixing was determined as a function of the Richardson number. A significant aspect ratio dependence was noted.;The results have applicability to the understanding and operation of Strategic Petroleum Reserves (SPR), where oil of different compositions are stored in underground salt caverns of aspect ratio∼ 0.1, and the stratification so introduced is evolving due to the caverns after degassification at the surface level.