Heat transport in Rayleigh-Bénard convection and angular momentum transport in Taylor-Couette flow: a comparative...

Rayleigh-Bénard 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-Bénard convection in air at Rayleigh number Ra=10⁷ and Taylor-Couette flow at shear Reynolds number Re_S=2×10⁴ 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.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'.