Coherent structures related to turbulent convection in channel flows

Abstract: We study the coherent structures related to the turbulent advection term in the turbulent kinetic energy equation using conditional averaging in channel flows at friction Reynolds numbers Re? = 180 and 590. Two types of conditional events are investigated: one is characterised by significant energy gain due to turbulent advection and the other is characterised by significant energy loss due to turbulent advection. Both types of events are associated with patterns composed of positive and negative turbulent advection areas aligned in the streamwise direction. The main difference is that positive and negative turbulent advection occur at different locations around quasi-streamwise vortices and hairpin vortices. Keywords: coherent structures, turbulent energy transfer, turbulent channel flow