Non-Oberbeck-Boussinesq effects in turbulent thermal convection in ethane close to the critical point

Abstract

As shown in earlier work (Ahlers et al., J. Fluid Mech. 569, p.409 (2006)), non-Oberbeck Boussinesq (NOB) corrections to the center temperature in turbulent Rayleigh-Benard convection in water and also in glycerol are governed by the temperature dependences of the kinematic viscosity and the thermal diffusion coefficient. If the working fluid is ethane close to the critical point the origin of non-Oberbeck-Boussinesq corrections is very different, as will be shown in the present paper. Namely, the main origin of NOB corrections then lies in the strong temperature dependence of the isobaric thermal expansion coefficient β(T). More precisely, it is the nonlinear T-dependence of the density ρ(T) in the buoyancy force which causes another type of NOB effect. We demonstrate that through a combination of experimental, numerical, and theoretical work, the latter in the framework of the extended Prandtl-Blasius boundary layer theory developed in Ahlers et al., J. Fluid Mech. 569, p.409 (2006). The latter comes to its limits, if the temperature dependence of the thermal expension coefficient β(T) is significant.

arXiv comment18 pages, 15 figures, 3 tables

References in corpus (14)

• Scaling in thermal convection: A unifying theory
• Thermal convection for large Prandtl numbers
• Rotations and cessations of the large-scale circulation in turbulent Rayleigh-Benard convection
• Orientation changes of the large-scale circulation in turbulent Rayleigh-Benard convection
• Plume motion and large-scale circulation in a cylindrical Rayleigh-Bénard cell
• Heat transport by turbulent Rayleigh-B'enard Convection in cylindrical cells with aspect ratio one and less
• The ultimate state of thermal convection
• Heat transport in turbulent Rayleigh-Benard convection: Effect of finite top- and bottom-plate conductivity
• Flow reversal in a simple dynamical model of turbulence
• Heat Transport in Turbulent Rayleigh-Benard Convection
• Absense of slow transients, and the effect of imperfect vertical alignment, in turbulent Rayleigh-Benard convection
• Non-Oberbeck-Boussinesq effects in two-dimensional Rayleigh-Benard convection in glycerol
• On the Heat Transfer in Rayleigh-Benard systems
• Heat Transfer in Turbulent Rayleigh-Benard Convection below the Ultimate Regime

Cited by in corpus (15)

• Large scale dynamics in turbulent Rayleigh-Benard convection
• AFiD-GPU: a versatile Navier-Stokes Solver for Wall-Bounded Turbulent Flows on GPU Clusters
• Convection in multiphase flows using Lattice Boltzmann methods
• Connecting flow structures and heat flux in turbulent Rayleigh-Bénard convection
• Flow states in two-dimensional Rayleigh-Bénard convection as a function of aspect-ratio and Rayleigh number
• Prandtl-Blasius temperature and velocity boundary layer profiles in turbulent Rayleigh-Bénard convection
• Heat transport by turbulent Rayleigh-Bénard convection for $\Pra\ \simeq 0.8$ and $4\times 10^{11} \alt \Ra\ \alt 2\times10^{14}$: Ultimate-state transition for aspect ratio $\Gamma =1.00$
• Enhanced heat transport by turbulent two-phase Rayleigh-Bénard convection
• Heat transport by turbulent Rayleigh-Bénard convection for $\Pra\ \simeq 0.8$ and $3\times 10^{12} \alt \Ra\ \alt 10^{15}$: Aspect ratio $\Gamma =0.50$
• Logarithmic temperature profiles of turbulent Rayleigh-Bénard convection in the classical and ultimate state for a Prandtl number of 0.8
• Thermal boundary layer profiles in turbulent Rayleigh-Bénard convection in a cylindrical sample
• Horizontal Structures of Velocity and Temperature Boundary Layers in 2D Numerical Turbulent Rayleigh-Bénard Convection
• Dynamics of Mixed Convective--Stably-Stratified Fluids
• Robustness of heat-transfer in confined inclined convection at high-Prandtl-number
• Azimuthal diffusion of the large-scale-circulation plane, and absence of significant non-Boussinesq effects, in turbulent convection near the ultimate-state transition