Large Eddy Simulation of Gravity Current Flow Past a Circular Cylinder Using Immersed Boundary Method

We investigated the flow of gravity currents past circular cylinders above the smooth bed. In order to simulate the gravity current interacting with cylinder, large eddy simulation (LES) coupled with a direct forcing/fictitious domain (DF/FD) method was employed. The hydrodynamic forces induced by the gravity current on a circular cylinder and the flow features were investigated according to a gap distance from location below the cylinder to the bed and Reynolds number. When the gravity current encounters the circular cylinder, the maximum drag force occurs regardless of gap distance. In addition, Von Karman vortex shedding emerges behind the circular cylinder for larger gap distance. In this regard, the results can be divided into impact, transient and quasi-steady stages based on the characteristics of the hydrodynamic forces varying with time, which is consistent with previous observations. Consequently, our numerical approach well simulated the flow of gravity currents past circular cylinders in good agreement with those of previous studies.