Vibration-induced boundary-layer destabilization achieves massive heat-transport enhancement

Abstract

Thermal turbulence is well known as a potent means to convey heat across space by a moving fluid. The existence of the boundary layers near the plates, however, bottlenecks its heat-exchange capability. Here, we conceptualize a mechanism of thermal vibrational turbulence that breaks through the boundary-layer limitation and achieves massive heat-transport enhancement. When horizontal vibration is applied to the convection cell, a strong shear is induced to the body of fluid near the conducting plates, which destabilizes thermal boundary layers, vigorously triggers the eruptions of thermal plumes, and leads to a heat-transport enhancement by up to 600%. We further reveal that such a vibration-induced shear can very efficiently disrupt the boundary layers. The present findings open a new avenue for research into heat transport and will also bring profound changes in many industrial applications where thermal flux through a fluid is involved and the mechanical vibration is usually inevitable.

The effect of Prandtl number on turbulent sheared thermal convection

“…2018 a ), which also coincides with an enhanced Nusselt number and which has been associated with the onset of the ultimate regime. The same coincidence of the development of a log layer and an enhanced heat transfer had also been found by Wang, Zhou & Sun (2020 a ) for high frequency horizontal vibration of the RB cell. Here, in our present simulations, the more is decreased, the harder it becomes for the wall shear to disturb the thermal plumes and, as a result, at and , the log scaling cannot be attained in our simulations.…”

Periodically Modulated Thermal Convection

“…In particular, we calculate the transition between the different regimes in phase space and show how they depend on the Rayleigh and Prandtl numbers, which represent the ratios between buoyancy and viscosity and between momentum diffusivity and thermal diffusivity, respectively. Our modulation method is complementary to hitherto used concepts of using additional body force or modifying the spatial structure of the system to enhance heat transport, for example, adding surface roughness [30][31][32], shaking the convection cell [33], including additional stabilizing forces through geometrical modification [34][35][36], rotation [37], inclination [38,39], or a second stabilizing scalar field [40].…”

Near wall Prandtl number effects on velocity gradient invariants and flow topologies in turbulent Rayleigh–Bénard convection

“…Finally, it has been ensured a-posteriori that the chosen grid resolution is sufficient by ensuring y + and y + √ Pr (where y + = ρu τ y/µ with u τ = √ τ w /ρ , τ w and y being the friction velocity, wall shear stress magnitude and wall normal distance of the wall adjacent grid point, respectively) remains smaller than unity. For the present analysis, Cartesian grids of 250 3 , 460 3 and 700 3 ( 150 3 , 230 3 and 490 3 ) have been used for Pr = 1 ( Pr = 320 ) simulations of Ra = 10 7 , Ra = 10 8 and Ra = 10 9 , respectively.…”

“…Recently, immense heat transport enhancement (e.g. 500 %) was reported for Rayleigh–Bénard convection applications, by using water-heavy liquid (hydrofluoroether) mixture 2 and vibration-induced boundary-layer destabilization 3 .…”

“…Equations (2)(3)(4) are solved in a coupled manner in conjunction with the following boundary conditions. The simulation configuration is schematically shown in Fig.…”