The helicity of the velocity field for cellular convection in a rotating layer
| Autor: | A. V. Getling |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Convection
Physics Prandtl number Astronomy and Astrophysics Mechanics Rayleigh number Helicity Compressible flow Physics::Fluid Dynamics Polytrope symbols.namesake Classical mechanics Space and Planetary Science symbols Astrophysics::Solar and Stellar Astrophysics Magnetohydrodynamics Convection cell |
| Zdroj: | Astronomy Reports. 56:395-402 |
| ISSN: | 1562-6881 1063-7729 |
| DOI: | 10.1134/s1063772912040038 |
| Popis: | The helicity of a cellular convective flow in a horizontal layer of a compressible fluid (gas) heated from below and rotating about the vertical axis is studied using finite-difference numerical simulations. The medium is assumed to be polytropically stratified. A thermal perturbation that produces a system of Benard-type hexagonal convection cells is introduced at the initial time. Next, the cells are deformed by the action of the Coriolis force; however, at some stage of the evolution, the flow is nearly steady (at later times, the cells break down). For given Rayleigh and Prandtl numbers, the velocity-field helicity for this stage averaged over the layer increases with decreasing polytrope index (i.e., with increasing the curvature of the static entropy profile) and has a maximum at a certain rotational velocity of the layer. Numerical simulations of such quasi-ordered convective flows should reduce the uncertainties in estimates of the helicity, a quantity important for the operation of MHD dynamos. |
| Databáze: | OpenAIRE |
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