Peculiar behavior of thermally stratified channel flow under non-Boussinesq condition

Abstract

Buoyancy affected turbulent flow in a channel is numerically simulated via LES, subjected to large temperature gradient. Temperature dependent fluid properties like viscosity (μ) and thermal conductivity (κ) considered as variable as Boussinesq assumption fails to capture the insight physics. With increased stratification, turbulent momentum and buoyancy fluxes decreased at an alarming rate in the core of the channel due to the formation of some wave like structures (IGW). The most striking feature produced by the temperature dependence of viscosity is flow relaminarization on the hot side of the channel (where viscosity is higher) and movement of IGW from core to hot side. Pronounced modifications in turbulent structure are observed qualitatively and quantitatively, and the deviation in the behavior is due to the non-Boussinesq assumption.