OpenFOAM Simulation of Gravity-Current Head Impacted on The Structure on The Sea Floor

Large-eddy simulations of a gravity current impact on a circular cylinder were conducted using the twoLiquid MixingFoam open-source solver. The simulations determine the transient development of the drag and lift forces by using five sub-grid scale (SGS) turbulence models: (i) the Smagorinsky SGS model, (ii) the Smagorinsky SGS model with the van Driest damping, (iii) the dynamic SGS model with Lagrangian average, (iv) the wall-adapting local eddy-viscosity SGS model, and (v) the dynamic one k-equation eddy-viscosity model. The comparison of the model simulations with the laboratory measurements has shown the dynamic one k-equation eddy-viscosity model to be superior; it produced the best results in close agreement with the laboratory experiments. On the other hand, the Smagorinsky SGS model has under predicted both the drag and lift forces. The dynamic Lagrangian model and the wall-adapting local eddy-viscosity model have produced acceptable drag force but not the lift force. The drag and lift coefficients obtained from the simulation and the experiment were significantly greater than the known coefficients for uniform crossflow suggesting the dependence of the coefficients on the reflection of internal waves and therefore on the densimetric Froude number.