| FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS) |
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Thermal Convection in a Tilted Rectangular Cell with Aspect Ratio 0.5 |
| Qi Wang1, Bo-Lun Xu1, Shu-Ning Xia2, Zhen-Hua Wan1**, De-Jun Sun1** |
1Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027
2Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072
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| Cite this article: |
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Qi Wang, Bo-Lun Xu, Shu-Ning Xia et al 2017 Chin. Phys. Lett. 34 104401 |
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Abstract Thermal convection in a three-dimensional tilted rectangular cell with aspect ratio 0.5 is studied using direct numerical simulations within both Oberbeck–Boussinesq (OB) approximation and strong non-Oberbeck–Boussinesq (NOB) effects. The considered Rayleigh numbers $Ra$ range from $10^5$ to $10^7$, the working fluid is air at 300 K, and the corresponding Prandtl number $Pr$ is 0.71. Within the OB approximation, it is found that there exist multiple states for $Ra=10^5$ and hysteresis for $Ra=10^6$. For a relatively small tilt angle $\beta$, the large-scale circulation can either orient along one of the vertical diagonal planes (denoted by $M_{\rm d}$ mode) or orient parallel to the front wall (denoted by $M_{\rm p}$ mode). Which of the two modes transports heat more efficiently is not definitive, and it depends on the Rayleigh number $Ra$. For $Ra=10^7$ and $\beta=0^\circ$, the time-averaged flow field contains four rolls in the upper half and lower half of the cell, respectively, $M_{\rm d}$ and $M_{\rm p}$ modes only developing in tilted cells. By investigating NOB effects in tilted convection for fixed $Ra=10^6$, it is found that the NOB effects on the Nusselt number $Nu$, the Reynolds number $Re$ and the central temperature $T_{\rm c}$ for different $\beta$ ranges are different. NOB effects can either increase or decrease $Nu$, $Re$ and $T_{\rm c}$ when $\beta$ is varied.
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Received: 28 June 2017
Published: 27 September 2017
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| PACS: |
44.25.+f
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(Natural convection)
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47.20.Bp
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(Buoyancy-driven instabilities (e.g., Rayleigh-Benard))
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47.27.te
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(Turbulent convective heat transfer)
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47.55.pb
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(Thermal convection)
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| Fund: Supported by the National Natural Science Foundation of China under Grant Nos 11572314, 11232011 and 11621202, and the Fundamental Research Funds for the Central Universities. |
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