Wall modes in rotating penetrative internally heated convection
Rotating internally heated convection has been studied almost exclusively in laterally periodic domains, which cannot support the sidewall-attached modes that appear for sufficient rotation rates in rotating Rayleigh--Bénard convection in containers. We conduct direct numerical simulations of internally heated convection with isothermal plates and an adiabatic sidewall in cylinders of aspect ratio $Γ= 1/2$, $1$, and $2$ at $\Ra = 10^8$ and $\Pran = 1$, comparing them with a doubly periodic layer. When rotation is strong enough to stabilise the flow in a doubly periodic layer at the same $R$ ($\Ek \lessapprox 2 \times 10^{-5}$), the cylinders continue transporting heat via a wall mode down to $\Ek = 5.62 \times 10^{-6}$. This mode consists of a wave attached to the sidewall, with a radial thickness of roughly $0.03$ layer depths independent of $Γ$, leaving a stationary interior. Although unstable stratification is confined to the upper half of the conductive state, the mode also penetrates the lower half while retaining stable mean stratification in the measured lower-layer interval. Its azimuthal wavenumber scales roughly with $Γ$, yielding a wall parallel wavelength on the order of the layer depth, and it drifts retrograde as a rigid wave slower in wider cylinders and at lower $\Ek$. Analogous to rotating Rayleigh--Bénard convection, the wall modes reported here extend the observed range of sustained convection relative to the periodic reference and may complicate experimental comparisons.