Effects of Thermal Boundary Condition on the Formation of Tropical Cyclone-like Vortex in Rotating Convection*

Past studies empirically showed that there is a specific combination of Reynolds and Ekman numbers in rotating convective flows of a Boussinesq fluid allowing the formation of a tropical cyclone-like vortex (TCLV) with an eye. Axisymmetric flows with adiabatic sidewall were considered in those studies. We seek to find an answer to the question, would TCLV appear if the axisymmetric conditions are relaxed for the same Reynolds and Ekman numbers? This objective is addressed by conducting rotating convective flow simulations in a shallow cylindrical domain with the same boundary conditions (BCs) used for the axisymmetric calculations. It is observed that the flow becomes chaotic with no TCLV, however, TCLV emerges when the sidewall BC is changed from adiabatic to isothermal. This is because of a localised retrograde travelling wave near the sidewall which helps the emergence of a stronger primary poloidal flow leading to the formation of TCLV. This is observed for a range of Reynolds and Ekman numbers.