Local energy dissipation rate balances local heat flux in the center of turbulent thermal convection

The local kinetic energy dissipation rate _u,c in Rayleigh-Bénard convection cell was measured experimentally using the particle tracking velocimetry method, with varying Rayleigh number Ra, Prandtl number Pr, and cell height H. It is found that _u,c/(κ3H ^-4)=1.05×10^-4Ra1.55^±0.02Pr1. 15^±0.38. The Ra and H dependencies of the measured results are found to be consistent with the assumption made for the bulk energy dissipation rate _u,bulk in the Grossmann-Lohse model. A remarkable finding of the study is that _u,c balances the directly measured local Nusselt number Nu_c in the cell center, not only scalingwise but also in magnitude.