A Study of the Interaction of a Gravity Current With a Square Cylinder Using Two-Dimensional Numerical Simulations

We studied the interaction of a compositional lock-exchange gravity current with a square cylinder at moderate Reynolds numbers using two-dimensional high-resolution simulations. Recent experimental work obtained measurements of the drag and lift for circular and rectangular cylinders. However, a detailed quantitative description of the flowfield was not given. Our objectives were to provide such description and, from it, explain the physical mechanisms behind the values and the time variation of the drag and lift coefficients. Such information is valuable for the design of submarine structures under the potential impact of gravity currents. Our numerical results agreed well with available experimental measurements. The interaction can be divided into impact, transient, and quasisteady-state stages. The shedding of vortices during the impact stage had an important effect on the drag and lift variation with time. For example, for a specific set of parameters, the suction created by these vortices produced about 40–50% of the drag. The maximum drag and the maximum lift amplitude occurred during the initial impact stage, and their minimum values were found when the square cylinder was closer to the bottom wall.