Bulletin of the American Physical Society
74th Annual Meeting of the APS Division of Fluid Dynamics
Volume 66, Number 17
Sunday–Tuesday, November 21–23, 2021; Phoenix Convention Center, Phoenix, Arizona
Session H05: Porous Media Flows: Convection and Heat Transfer I |
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Chair: JEAN-FRANÇOIS LOUF, Auburn Room: North 121 C |
Monday, November 22, 2021 8:00AM - 8:13AM |
H05.00001: Buoyant convection in a porous medium with an inclined permeability jump: An experimental investigation of filling box-type flows Bharath S Kattemalalawadi, Morris R Flynn Employing the concept of a ‘filling-box’ model, we report upon experiments featuring a dense, Boussinesq plume falling through a two-layered porous medium characterized by a high permeability upper layer and a low permeability lower layer. Upon striking the permeability jump, the plume fluid bifurcates leading to the formation of a pair of (up- and downdip) ‘primary’ gravity currents. The associated early time spreading behavior has been investigated in our previous work (Bharath et.al, JFM, vol. 902, 2020). It was shown that the primary gravity currents reach a state of runout wherein the inflow from the plume is precisely matched by the outflow due to draining. As an extension of our previous work, we herein examine the flow evolution over longer times and thereby study the impact of the lower layer depth. To this end, we characterize the formation of `secondary’ gravity currents, which form when the fluid draining from the underside of the gravity currents strikes the bottom (impermeable) boundary. As a consequence of the propagation of these secondary gravity currents, the primary gravity currents may become remobilized. Later, the gravity currents flow become impeded by the vertical sidewall boundaries, allowing us to categorize two qualitatively different filling regimes. |
Monday, November 22, 2021 8:13AM - 8:26AM |
H05.00002: Influence of non-Darcy effects on scaling laws of convection in Hele-Shaw flows Marco De Paoli, Mobin Alipour, Alfredo Soldati In this work, we examined the influence of non-Darcy terms on convective dissolution in confined porous media. We performed experiments in Hele-Shaw configuration and we focused on buoyancy-driven convection, where the flow is controlled by the Rayleigh-Darcy number, Ra, which measures the strength of convection compared to diffusion. The Hele-Shaw cell is suitable to mimic Darcy flows only under certain geometrical constraints, and precise limits exist for Ra and cell geometry beyond which the flow exhibits non-Darcy effects. We performed experiments in Rayleigh-Bénard-like configuration and we clearly identify the application limits of Darcy flow assumptions. Besides confirming previous theoretical predictions, current results are of relevance in the context of porous media flows - which are often studied experimentally with Hele-Shaw setups. Using our original datasets, we have been able to explain and reconcile the discrepancies observed between scaling laws previously proposed for Rayleigh-Bénard-like experiments and simulations in similar contexts. Specifically, we discuss the conditions beyond which Hele-Shaw experiment results are influenced by three-dimensional effects. |
Monday, November 22, 2021 8:26AM - 8:39AM |
H05.00003: Effective solvent-solute transport across micro-structured thin membranes Giuseppe A Zampogna, Pier Giuseppe Ledda, Francois Gallaire A multi-scale homogenization based model to simulate the transport of a passive solute across a membrane and the hydrodynamic of the surrounding fluid solvent is presented. |
Monday, November 22, 2021 8:39AM - 8:52AM |
H05.00004: Experimental investigation on Rayleigh-Taylor instability in confined porous media Diego Perissutti, Marco De Paoli, Alfredo Soldati Experiments in Hele-Shaw cells are used to mimic the problem of Rayleigh-Taylor instability in confined porous media. Rayleigh-Taylor instability phenomena arise when a layer of heavy fluid sits on top of a layer of a lighter fluid. The flow is initially controlled by diffusion, but rather quickly the action of gravity produces efficient fluid mixing in the entire domain. Small fluctuations of the interface separating the two fluid layers produce larger structures that eventually drive the flow into a nonlinear convective stage. The competition between buoyancy and diffusion is measured by the Rayleigh-Darcy number, the value of which controls the entire dynamics of the flow. We employ an optical method to obtain accurate measurements of the solute concentration and we perform experiments for a wide range of Rayleigh-Darcy numbers. The fluids consist of water and an aqueous solution of potassium permanganate. We characterize the flow evolution with the mixing length (a suitably defined extension of the mixing region) and with the degree of mixing of the two fluids. In this work, mixing is quantified by the mean scalar dissipation rate. The results obtained are compared against previous experimental and numerical works. |
Monday, November 22, 2021 8:52AM - 9:05AM |
H05.00005: Acoustic flow in porous media Ofer Manor We calculate the acoustic flow – the steady drift of fluid mass to appear due to the convection of momentum along the path of an acoustic wave – in a porous medium. In particular, we suggest a mechanism to explain observations of acoustic contributions to mass transport in porous media at geological, unit operation, and lab on a chip length scales. We study three limits for the case of an acoustic planar wave (that is, sound or ultrasound waves) whose wavelength is large compared to the pore size. We commence our analysis at the ideal limit of similar acoustic properties in the solid and fluid. The acoustic flow may then be treated according with the Darcy theory for flow through porous media in addition to a correction for the average azimuth of the pores compared to the acoustic path. The two other limits are taken within the framework of a rigid porous frame. The presence of a flow forcing mechanism to result from the viscous dissipation of the acoustic wave at the solid surface of the pores in this case hinders the direct use of the Darcy theory. The analysis is conducted by a detailed calculation of the convective transport of mass through cylindrical pores of similar size but arbitrary inclination, where we consider large and medium to small pore diameter limits. |
Monday, November 22, 2021 9:05AM - 9:18AM |
H05.00006: Towards the ultimate regime in Rayleigh-Darcy convection Francesco Zonta, Sergio Pirozzoli, Marco De Paoli, Alfredo Soldati Numerical simulations are used to probe Rayleigh-Darcy convection in fluid-saturated porous media towards the ultimate regime. The present three-dimensional dataset, up to Rayleigh-Darcy number Ra=80 000, suggests that the appropriate scaling of the Nusselt number is Nu=0.0081Ra+0.067Ra^{0.61}, fitting the computed data for Ra>1000. Extrapolation of current predictions to the ultimate linear regime yields the asymptotic law Nu=0.0081Ra, about 16% less than indicated in previous studies. Upon examination of the flow structures near the boundaries, we confirm previous indications of small flow cells hierarchically nesting into supercells, and we show evidence that the supercells at the boundary are the footprints of the megaplumes that dominate the interior part of the flow. The present findings pave the way for more accurate modeling of geophysical systems, with special reference to geological CO_{2} sequestration. |
Monday, November 22, 2021 9:18AM - 9:31AM |
H05.00007: Brinkman number effect and Conjugate heat transfer in a porous microchannel Ian Guillermo Monsivais Montoliu, Federico Mendez, Jose Lizardi The problem of conjugate heat transfer in a fully saturated porous medium confined in a microchannel between parallel plates is analyzed. Two conjugate heat transfer parameters were defined in the microchannel wall and in the fluid. It was found that the values of these parameters have certain limits under which, longitudinal temperature gradients can occur both in the wall and in the porous medium. Additionally, we studied the effects of the Darcy number Da and the Brinkman number Br, on fluid and wall temperature profiles for different values of the conjugate heat transfer parameters. Finally, several values of the Peclet number are analyzed in order to find out which of them promotes longitudinal (axial) heat conduction in the fluid and also in the wall of the microchannel. The main objective of this work is to determine for which Brinkman values the viscous dissipation effects are more important than the longitudinal heat conduction effects in the microchannel wall. |
Monday, November 22, 2021 9:31AM - 9:44AM |
H05.00008: Modelling the Navier-Stokes-Darcy-Boussinesq system Matthew McCurdy To investigate convection in coupled fluid-porous media systems, we analyze the Navier-Stokes-Darcy Heat model with numerical simulations conducted via a finite element method. To help validate numerical results, we compare our simulations against stability thresholds for the system. |
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