Lagrangian dynamics and heat transfer in porous media convection

Abstract

We report a numerical study of Rayleigh--Bénard convection through random porous media using pore-scale modelling, focusing on the Lagrangian dynamics of fluid particles and heat transfer for varied porosities $\varphi$. Due to the interaction between the porous medium and the coherent flow structures, the flow is found to be highly heterogeneous, consisting of convection channels with strong flow strength and stagnant regions with low velocities. The modifications of flow field due to porous structure have a significant influence on the dynamics of fluid particles. Evaluation of the particle displacement along the trajectory reveals the emergence of anomalous transport for long times as $\varphi$ is decreased, which is associated with the long-time correlation of Lagrangian velocity of the fluid. As porosity is decreased, the cross-correlation between the vertical velocity and temperature fluctuation is enhanced, which reveals a mechanism to enhance the heat transfer in porous media convection.

15 pages, 7 figures

References in corpus (7)

• Multifractal statistics of Lagrangian velocity and acceleration in turbulence
• Bubbly and Buoyant Particle-Laden Turbulent Flows
• Continuous Time Random Walks for the Evolution of Lagrangian Velocities
• Local pore size correlations determine flow distributions in porous media
• From Rayleigh-Bénard convection to porous-media convection: how porosity affects heat transfer and flow structure
• Effects of Pore-scale on the Macroscopic Properties of Natural Convection in Porous Media
• Buoyancy-driven flow through a bed of solid particles produces a new form of Rayleigh-Taylor turbulence

Cited by in corpus (3)

• Enhanced Laboratory X-ray Particle Tracking Velocimetry With Newly Developed Tungsten-Coated O(50 $\mu$m) Tracers
• Fluids flow in granular aggregate packings reconstructed by high-energy X-ray computed tomography and lattice Boltzmann method
• Pore-scale statistics of temperature and thermal energy dissipation rate in turbulent porous convection