Direct numerical simulation of Nusselt number scaling in rotating Rayleigh–Bénard convection

• We performed direct numerical simulations of rotating Rayleigh–Bénard convection.
• We analyzed the scaling of the Nusselt number with the Rayleigh number.
• The scaling exponent is effectively independent of the rotation rate, at high Rayleigh numbers.
• Rotation could increase the heat transfer up to 18%.
• Rotating convection organizes itself in vertical vortices.

We report results from Direct Numerical Simulation (DNS) of rotating Rayleigh–Bénard convection, regarding the scaling of heat transfer with the Rayleigh number for rotating systems at a fixed rate of rotation. The Prandtl number, Pr=6.4Pr=6.4, is kept constant. We perform simulations, using a spectral element method, for Rayleigh numbers Ra   from 106106 to 109109, and Rossby numbers Ro   from 0.09 to ∞∞. We find that the Nusselt number Nu scales approximately with a power 2/7 of Ra at sufficiently high Ra for all Ro. The value of Ra beyond which this Nusselt scaling is well established increases with decreasing Ro. Depending on the rotation rate, the Nusselt number can increase up to 18% with respect to the non-rotating case.