Thermoconvective instabilities to explain the main characteristics of a dust devil-like vortex
In this paper we show numerically that the main characteristics of a dust devil-like vortex: vertical vorticity generation, eye formation, and tilting of the eye/axis of rotation, can be explained by thermoconvective mechanisms. By considering a cylinder non-homogeneously heated from below we prove...
| Autores: | , , |
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| Tipo de documento: | artigo |
| Data de publicação: | 2015 |
| País: | España |
| Recursos: | Universidad de Castilla-La Mancha |
| Repositório: | RUIdeRA. Repositorio Institucional de la UCLM |
| OAI Identifier: | oai:ruidera.uclm.es:10578/40293 |
| Acesso em linha: | https://hdl.handle.net/10578/40293 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Navier–Stokes equations Spectral methods Thermoconvective instabilities Vortex generation |
| Resumo: | In this paper we show numerically that the main characteristics of a dust devil-like vortex: vertical vorticity generation, eye formation, and tilting of the eye/axis of rotation, can be explained by thermoconvective mechanisms. By considering a cylinder non-homogeneously heated from below we prove that an intense localized heating on the ground generates a convective stationary axisymmetric flow that begins to spiral up around a central axis when perturbation vertical vorticity is permitted and a critical vertical temperature gradient is exceeded, thus forming an axisymmetric vortex. If the intense heating on the ground is not too localized and the temperature gradient continues increasing, central downdrafts appear in the vortex and an eye is formed. We show that the axisymmetric vortex loses stability towards a new state for which the axisymmetry is broken, the axis of rotation or proper eye displaces from the center and tilts. The vortical states found are comparable to dust devils. These findings establish the relevance of thermoconvection on the formation and evolution of these atmospheric phenomena. |
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