Charlie Lloyd

Internal wave dynamics in stratified plane Poiseuille flow

Stratified turbulent flows are commonplace in environmental, atmospheric, and industrial settings, and are deeply rich in dynamics. Here we investigate stably stratified plane Poiseuille (or channel) flow using direct numerical simulation and linear stability analysis, where stratification is imposed through a temperature difference between the upper and lower boundaries. Under suitably high Reynolds and Richardson numbers the stratified channel flow is highly coherent and vertically partitioned, with shear-dominated regions near the walls and a buoyancy dominated region in the core. In this work we find that the buoyancy dominated channel core is host to a series of internal waves which dominate spectra over a wide range of temporal frequencies and appear to obey a linear wave dispersion relation. This talk will focus on the generation mechanisms and nature of these waves, and the key features required of the background flow to obtain such large-scale coherent structures in an otherwise turbulent flow.