A numerical model of mixing and convection driven by surface buoyancy flux
MetadataShow full item record
This thesis studies mixing and convection in a rectangular basin driven by a specified heat flux at the surface. A numerical model is constructed for this purpose. The main focus of the study is on the density and circulation structure resulting from the thermal forcing. In chapter two, a simple vertical one-dimensional model is developed to examine the mixing processes under a given surface heat flux. In order to simulate strong vertical mixing in the region where stratification is unstable, turbulent processes are modeled by a convective overturning parameterization of eddy viscosity and diffusivity. The results show that the density structure is strongly affected by the convective overturning adjustment as surface cooling prevails, and the resulting density field is nearly depth independent. In chapter three, a more complicated two-dimensional model is constructed to simulate mixing and circulation in a vertical rectangular basin with rigid boundaries. The aspect ratio of the basin ranges from 1 to 0.001 and Rayleigh number from 104 to 2 x 1012. It is found that the circulation pattern is dominated by these two important numbers. The roles of density overturning and density-momentum overturning mixing are further investigated. The results show that the convective overturning not only homogenizes the density field in the unstably stratified region but also contributes to increase the circulation. A crude scale analysis of the system shows that the characteristics of the density and momentum fields from the analysis agree well with the numerical results.
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1989
Showing items related by title, author, creator and subject.
McDermott, Jill M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2015-02)This thesis examines the controls on organic, inorganic, and volatile species distributions in hydrothermal fluids venting at Von Damm and Piccard, two vent fields at the ultraslow spreading Mid-Cayman Rise, Earth’s deepest ...
Drenkard, Elizabeth J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2015-02)Global climate models project a 21st century strengthening of the Pacific Equatorial Undercurrent (EUC). The consequent increase in topographic upwelling of cool waters onto equatorial coral reef islands would mitigate ...
Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers deMartin, Brian J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007-02)Oceanic spreading centers are sites of magmatic, tectonic, and hydrothermal processes. In this thesis I present experimental and seismological constraints on the evolution of these complex regions of focused crustal ...