Mixed insulating and conducting thermal boundary conditions in Rayleigh-Bénard convection
| Autor: | Roberto Verzicco, Rodolfo Ostilla-Mónico, Detlef Lohse, Erwin P. van der Poel, Dennis Bakhuis |
|---|---|
| Přispěvatelé: | Physics of Fluids |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Convection
Materials science Prandtl number Bulk temperature UT-Hybrid-D Settore ING-IND/06 Bénard convection Turbulent convection 01 natural sciences 010305 fluids & plasmas Benard convection turbulent convection Physics::Fluid Dynamics symbols.namesake 0103 physical sciences Thermal Boundary value problem Rayleigh scattering 010306 general physics Rayleigh–Bénard convection Mechanical Engineering Mechanics Physics - Fluid Dynamics Condensed Matter Physics Mechanics of Materials Heat transfer symbols |
| Zdroj: | Journal of Fluid Mechanics Journal of fluid mechanics, 835, 491-511. Cambridge University Press |
| ISSN: | 0022-1120 |
| Popis: | A series of direct numerical simulations of Rayleigh-B\'enard convection, the flow in a fluid layer heated from below and cooled from above, were conducted to investigate the effect of mixed insulating and conducting boundary conditions on convective flows. Rayleigh numbers between $\text{Ra}=10^7$ and $\text{Ra}=10^9$ were considered, for Prandtl numbers $\text{Pr}=1$ and $\text{Pr}=10$. The bottom plate was divided into patterns of conducting and insulating stripes. The size ratio between these stripes was fixed to unity and the total number of stripes was varied. Global quantities such as the heat transport and average bulk temperature and local quantities such as the temperature just below the insulating boundary wall were investigated. For the case with the top boundary divided into two halves, one conducting and one insulating, the heat transfer was found to be approximately two thirds of the fully conducting case. Increasing the pattern frequency increased the heat transfer which asymptotically approached the fully conducting case, even if only half of the surface is conducting. Fourier analysis of the temperature field revealed that the imprinted pattern of the plates is diffused in the thermal boundary layers, and cannot be detected in the bulk. With conducting-insulating patterns on both plates, the trends previously described were similar, however, the half-and-half division led to a heat transfer of about a half of the fully conducting case instead of two-thirds. The effect of the ratio of conducting and insulating areas was also analyzed, and it was found that even for systems with a top plate with only $25\%$ conducting surface, heat-transport of $60\%$ of the fully conducting case can be seen. Changing the 1D stripe pattern to 2D checkerboard tessellations does not result in a significantly different response of the system. Comment: Submitted to JFM |
| Databáze: | OpenAIRE |
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