Thermoconvective vortices in a cylindrical annulus with varying inner radius

Abstract

This paper shows the influence of the inner radius on the stability and intensity of vertical vortices, qualitatively similar to dust devils and cyclones, generated in a cylindrical annulus non-homogeneously heated from below. Little relation is found between the intensity of the vortex and the magnitude of the inner radius. Strong stable vortices can be found for both small and large values of the inner radius. The Rankine combined vortex structure, that characterizes the tangential velocity in dust devils, is clearly observed when small values of the inner radius and large values of the ratio between the horizontal and vertical temperature differences are considered. A contraction on the radius of maximum azimuthal velocity is observed when the vortex is intensified by thermal mechanisms. This radius becomes then nearly stationary when frictional force balances the radial inflow generated by the pressure drop in the center, despite the vortex keeps intensifying. These results connect with the behavior of the radius of the maximum tangential wind associated with a hurricane.

On the rapid intensification of Hurricane Wilma (2005). Part IV: Inner‐core dynamics during the steady radius of maximum wind stage

“…The role of frictional dissipation in preventing the RMW from collapsing is also confirmed by Castaño et al . (). In contrast, Wang and Wang () attributed the non‐contracting RMW structure during the RI of Typhoon Megi (2010) to the rapid release of latent heat in the outer spiral rain bands interacting with a low‐level synoptic depression in which the storm was embedded.…”

Secondary whirls in thermoconvective vortices developed in a cylindrical annulus locally heated from below

“…We have observed that the double circulation appears, when the primary vortex destabilizes [11], only forā < 0.5. Whenā ≥ 0.5 the bifurcation does not lead to a subvortex.…”

“…A vertical vortex is formed. The behavior of the particles in the vortex is a spiral up motion around the inner cylinder [10,11]. As R continues increasing in the range of stability of the vortex, the azimuthal velocity component u φ grows, the vortex intensifies, as shown in Fig.…”

“…The linear stability analysis of the axisymmetric vortex shows that it destabilizes through a oscillatory bifurcation of wavenumber k c = 1 [11,12]. Fig.…”

“…In Ref. [11] authors analyze the influence of the size of the radius of the inner cylinder on the structure, intensity and stability of the primary vortex developed. In Ref.…”