Extension of k-ω turbulence closure to two-phase sediment transport modelling: Application to oscillatory sheet flows

•Two-phase sediment transport model with k-ω fluid turbulence closure is presented.•Model is applied to wave-current and asymmetric wave sheet flows.•k-ω and k-ε closures produce similar results in two-phase sheet flow models.•Closure for additional dissipative terms is critical.

A number of turbulence closure schemes can be employed to numerically investigate near-bed wave boundary layer and sediment transport problems. We present an extension of the widely used k-ω turbulence model to two-phase sediment transport modelling. In this model, a transport equation is solved for the turbulence specific dissipation rate ω. For two-phase models, this equation is similar to the one for clear fluids with an additional term due to inter-phase interaction terms, which we will discuss. The new k-ω model is then applied to wave and current sheet flows. We compare the numerical results from the k-ω model and from an existing k-ε model against sheet flow experimental data collected in oscillatory water tunnels. Both models provide broadly similar numerical results. Nevertheless, the k-ω and k-ε models display different behaviour around flow reversal, and neither is able to fully reproduce observed suspension peak at flow reversal.