Turbulent mixed convection in vertical and horizontal channels
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| Format: | Preprint |
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2024
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| _version_ | 1866912125567369216 |
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| author | Howland, Christopher J. Yerragolam, Guru Sreevanshu Verzicco, Roberto Lohse, Detlef |
| author_facet | Howland, Christopher J. Yerragolam, Guru Sreevanshu Verzicco, Roberto Lohse, Detlef |
| contents | Turbulent shear flows driven by a combination of a pressure gradient and buoyancy forcing are investigated using direct numerical simulations. Specifically, we consider the setup of a differentially heated vertical channel subject to a Poiseuille-like horizontal pressure gradient. We explore the response of the system to its three control parameters: the Grashof number $Gr$, the Prandtl number $Pr$, and the Reynolds number $Re$ of the pressure-driven flow. From these input parameters, the relative strength of buoyancy driving to the pressure gradient can be quantified by the Richardson number $Ri=Gr/Re^2$. We compare the response of the mixed vertical convection configuration to that of mixed Rayleigh-Bénard convection and find a nearly identical behaviour, including an increase in wall friction at higher $Gr$ and a drop in the heat flux relative to natural convection for $Ri=O(1)$. This closely matched response is despite vastly different flow structures in the systems. No large-scale organisation is visible in visualisations of mixed vertical convection - an observation that is quantitatively confirmed by spectral analysis. This analysis, combined with a statistical description of the wall heat flux, highlights how moderate shear suppresses the growth of small-scale plumes and reduces the likelihood of extreme events in the local wall heat flux. Vice versa, starting from a pure shear flow, the addition of thermal driving enhances the drag due to the emission of thermal plumes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2403_07533 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Turbulent mixed convection in vertical and horizontal channels Howland, Christopher J. Yerragolam, Guru Sreevanshu Verzicco, Roberto Lohse, Detlef Fluid Dynamics Turbulent shear flows driven by a combination of a pressure gradient and buoyancy forcing are investigated using direct numerical simulations. Specifically, we consider the setup of a differentially heated vertical channel subject to a Poiseuille-like horizontal pressure gradient. We explore the response of the system to its three control parameters: the Grashof number $Gr$, the Prandtl number $Pr$, and the Reynolds number $Re$ of the pressure-driven flow. From these input parameters, the relative strength of buoyancy driving to the pressure gradient can be quantified by the Richardson number $Ri=Gr/Re^2$. We compare the response of the mixed vertical convection configuration to that of mixed Rayleigh-Bénard convection and find a nearly identical behaviour, including an increase in wall friction at higher $Gr$ and a drop in the heat flux relative to natural convection for $Ri=O(1)$. This closely matched response is despite vastly different flow structures in the systems. No large-scale organisation is visible in visualisations of mixed vertical convection - an observation that is quantitatively confirmed by spectral analysis. This analysis, combined with a statistical description of the wall heat flux, highlights how moderate shear suppresses the growth of small-scale plumes and reduces the likelihood of extreme events in the local wall heat flux. Vice versa, starting from a pure shear flow, the addition of thermal driving enhances the drag due to the emission of thermal plumes. |
| title | Turbulent mixed convection in vertical and horizontal channels |
| topic | Fluid Dynamics |
| url | https://arxiv.org/abs/2403.07533 |