Enhancing Heat Transport in Multiphase Rayleigh-Bénard Turbulence by Changing the Plate-Liquid Contact Angles

Abstract

This numerical study presents a simple but extremely effective way to considerably enhance heat transport in turbulent multiphase flows, namely by using oleophilic walls. As a model system, we pick the Rayleigh-Bénard setup, filled with an oil-water mixture. For oleophilic walls, e.g. using only $10\%$ volume fraction of oil in water, we observe a remarkable heat transport enhancement of more than $100\%$ as compared to the pure water case. In contrast, for oleophobic walls, the enhancement is then only about $20\%$ as compared to pure water. The physical explanation of the highly-efficient heat transport for oleophilic walls is that thermal plumes detach from the oil-rich boundary layer and are transported together with the oil phase. In the bulk, the oil-water interface prevents the plumes to mix with the turbulent water bulk. To confirm this physical picture, we show that the minimum amount of oil to achieve the maximum heat transport is set by the volume fraction of the thermal plumes. Our findings provide guidelines of how to optimize heat transport in thermal turbulence. Moreover, the physical insight of how coherent structures are coupled with one phase of a two-phase system has very general applicability for controlling transport properties in other turbulent multiphase flows.

arXiv comment11 pages, 4 figues

References in corpus (22)

• Large scale dynamics in turbulent Rayleigh-Benard convection
• Scaling in thermal convection: A unifying theory
• Thermal convection for large Prandtl numbers
• Radial boundary layer structure and Nusselt number in Rayleigh-Benard convection
• The unifying theory of scaling in thermal convection: The updated prefactors
• Comparison between two and three dimensional Rayleigh-Bénard convection
• Roughness-facilitated local 1/2 scaling does not imply the onset of the ultimate regime of thermal convection
• Convection in multiphase flows using Lattice Boltzmann methods
• Mixed convection in turbulent channels with unstable stratification
• The importance of bubble deformability for strong drag reduction in bubbly turbulent Taylor-Couette flow
• Turbulent thermal convection over rough plates with varying roughness geometries
• Confined Rayleigh-Bénard, Rotating Rayleigh-Bénard, and Double Diffusive Convection: A unifying view on turbulent transport enhancement through coherent structure manipulation
• Controlling heat transport and flow structures in thermal turbulence using ratchet surfaces
• Random Roughness of Boundary Increases Turbulent Convection Scaling Exponent
• Heat transport in boiling turbulent Rayleigh-Bénard convection
• Physical mechanisms governing drag reduction in turbulent Taylor-Couette flow with finite-size deformable bubbles
• Flow organization and heat transfer in turbulent wall sheared thermal convection
• Enhanced heat transport by turbulent two-phase Rayleigh-Bénard convection
• Experimental investigation of heat transport in homogeneous bubbly flow
• An efficient phase-field method for turbulent multiphase flows
• Global and local statistics in turbulent emulsions
• Catastrophic phase inversion in high-Reynolds number turbulent Taylor--Couette flow

Cited by in corpus (6)

• Heat transfer in turbulent Rayleigh-Bénard convection within two immiscible fluid layers
• Evaporating Rayleigh-Bénard convection: prediction of interface temperature and global heat transfer modulation
• Analysis of the heat transfer fluctuations in the Rayleigh-Bénard convection of concentrated emulsions with finite-size droplets
• Turbulent Rayleigh-Bénard convection with bubbles attached to the plate
• Role of interfacial stabilization in the Rayleigh-Bénard convection of liquid-liquid dispersions
• Dynamical regimes of thermally convective emulsions