The seawater encroachment in a coastal aquifer is studied by means of a mathematical model. In some aquifers the dispersion amalgamates the encroaching seawater and the discharging freshwater to produce an extensive zone of diffusion. The coupled nonlinear conservation equations of mass and of salt are formulated and solved by the finite element method with the aids of iteration and underrelaxation. The numerical procedure is verified by comparing solutions with known results in the literature. In this study the seawater encroachment in the Biscayne aquifer at Cutler area, Florida, is modeled; the numerical results are in good qualitative agreement with the field data obtained by Kohout.

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3D numerical simulation of flow fields in a combustion chamber of a scramjet engine using an SST turbulence model with an explicit compressibility correction was performed and the results were compared to the experimental results. The characteristics of the turbulent combustion flow fields were analyzed via the numerical results and presented. In order to identify the mechanisms of turbulent combustion in supersonic flows, the evolutions of governing dimensionless parameters in the flow fields were investigated based on the theory of combustion and the available numerical results. It was found that the supersonic combustion takes place in the region of fully developed turbulence and that the strongest effects of turbulence and combustion processes appear in the vicinity of the injector. The unsteady effects and the local flame extinction phenomenon induced by turbulent flows were found to be negligibly small, and the steady flamelet approximation will hold for practical applications. scramjet, turbulent combustion, flamelet approximation, numerical simulation Citation:Gao Z X, Lee C H. A numerical study of turbulent combustion characteristics in a combustion chamber of a scramjet engine.