Heat transport in Rayleigh-Benard convection and angular momentum transport in Taylor-Couette flow: a comparative study

TL;DR

This study compares heat and angular momentum transport in Rayleigh-Benard convection and Taylor-Couette flow, revealing similarities and differences in flow structures and fluctuations influenced by rotation at comparable Nusselt numbers.

Contribution

It provides a detailed comparison of local flow properties and transport mechanisms in two canonical turbulent flows at matched transport levels, highlighting the effects of rotation.

Findings

Good agreement in mean temperature and angular momentum profiles at specific rotation rates

Similar fluctuations in temperature and velocity components in boundary layers

Differences in fluctuations outside boundary layers increase with rotation

Abstract

Rayleigh-Benard convection and Taylor-Couette flow are two canonical flows that have many properties in common. We here compare the two flows in detail for parameter values where the Nusselt numbers, i.e. the thermal transport and the angular momentum transport normalized by the corresponding laminar values, coincide. We study turbulent Rayleigh-Benard convection in air at Rayleigh number Ra=1e7 and Taylor-Couette flow at shear Reynolds number Re_S=2e4 for two different mean rotation rates but the same Nusselt numbers. For individual pairwise related fields and convective currents, we compare the probability density functions normalized by the corresponding root mean square values and taken at different distances from the wall. We find one rotation number for which there is very good agreement between the mean profiles of the two corresponding quantities temperature and angular momentum. Similarly, there is good agreement between the fluctuations in temperature and velocity components. For the heat and angular momentum currents, there are differences in the fluctuations outside the boundary layers that increase with overall rotation and can be related to differences in the flow structures in the boundary layer and in the bulk. The study extends the similarities between the two flows from global quantities to local quantities and reveals the effects of rotation on the transport.