Pore-Resolving DNS of Turbulence at Sediment-Water Interface

We investigate turbulent flow penetration across sediment-water interfaces using pore-resolving direct numerical simulations. We carry out simulations of turbulent flow over a bed of fully resolved spherical particles at friction Reynolds number 180 and permeability Reynolds number from about 2 to 6. We use the volume-filtering immersed boundary method to represent the sediment grains, which have a size that varies from about 20 to 80 wall units, and resolve the flow within the pores. To validate the computational approach, we compare results from our pore-resolving DNS to published experimental data. The simulations show the degree of turbulence penetration within the sediment layer increases with permeability Reynolds number. This shows that permeability Reynolds number plays an important role in mass and momentum exchange across the sediment-water interface.