Wave‐Signal Entrainment Into Combined Flows: Consequences for Sediment Transport, Signal Dislocation, and Turbulence

Combined flows in which the unidirectional flow is a turbidity current that is superimposed by gravity waves, have complex flow dynamics. We present data from laboratory‐generated combined flows, that demonstrate the effects a wave field has on turbidity current sediment transport and the dynamics of mixing. The combined flows had a net increase in down slope sediment transport and the measured wave velocities within the body of the combined flows were both greater in magnitude and statistically distinct from those measured in the wave field alone. To explain these findings, we applied a turbulence model and an eddy viscosity model to our measured velocity data of the current. We found that the sediment transport effects are explained by two distinct modes of waves influence over the dynamics of current mixing. In one mode, combined flows are isolated from the ambient fluid in a “jet‐sharpening” process. In the other mode, the combined flows' Reynolds stress is enhanced, and both cases result in increased sediment transport. Our results have important implications for understanding modern transport in wave‐influenced hyperpycnal flows in the modern and geologic record.