Bulletin of the American Physical Society
72nd Annual Meeting of the APS Division of Fluid Dynamics
Volume 64, Number 13
Saturday–Tuesday, November 23–26, 2019; Seattle, Washington
Session G38: Porous Media Flow Convection and Heat Transfer |
Hide Abstracts |
Chair: Morris Flynn, University of Alberta Room: 620 |
Sunday, November 24, 2019 3:48PM - 4:01PM |
G38.00001: Heat transfer and flow structures of Rayleigh-Benard convection in regular porous media Shuang Liu, Linfeng Jiang, Kai Leong Chong, Xiaojue Zhu, Zhenhua Wan, Roberto Verzicco, Richard Stevens, Detlef Lohse, Chao Sun We report on a numerical study of porous media Rayleigh-Benard (RB) convection for the Rayleigh number $Ra$ from $10^5$ to $10^{10}$ at various porosities $\phi$. The porous media is constructed by an array of circular, solid obstacles locating on a square lattice. For a given $\phi$ two flow regimes are identified with different heat transport properties and flow structures. In the small-$Ra$ regime the heat transport is reduced compared with the classical RB convection without obstacles and the flow is dominated by coherent thermal plumes, while in the large-$Ra$ regime the heat transport is enhanced and the flow is dominated by fragmented plumes. The Nusselt number follows different scaling behaviors in the two regimes, and the regime crossover occurs when the thermal boundary layer thickness is comparable to the particle separation. [Preview Abstract] |
Sunday, November 24, 2019 4:01PM - 4:14PM |
G38.00002: Buoyant convection in porous media: multiple layers with inclined permeability jump Bharath Kattemalalawadi, Chunendra K. Sahu, Morris R. Flynn We report upon an experimentally-validated theoretical investigation of buoyancy driven flow in a two-layered porous media. The upper- and lower-layers are characterized by different permeabilities and feature a sloping boundary (or permeability jump) in between. The flow of dense fluid originates as a plume in the upper-layer that then forms up- and down-dip gravity currents. We present coupled plume and gravity current equations, which are solved numerically along with a set of initial- and boundary-conditions. The governing equations assumes miscible Darcy flow with a sharp-interface between the gravity currents and surrounding ambient. Our scaling analysis reveals the importance of four non-dimensional parameters for describing the along- and cross-jump flows. The theoretical results predict the (i) (time-dependent) fraction of flow up- vs. downdip, (ii) (time-dependent) flow draining into the lower-layer from the underside of the gravity currents, and (iii) up- and downdip run-out lengths. Experimental images further reveal the formation of two distinct interfaces, namely a sharp- and dispersed-interface. Theoretical predictions accurately capture the time evolution of the sharp-interface as measured experimentally. [Preview Abstract] |
Sunday, November 24, 2019 4:14PM - 4:27PM |
G38.00003: Transition of convection in coupled fluid-porous media systems Matthew McCurdy In superposed fluid-porous media systems, the ratio of the fluid height to the porous medium height exerts a significant influence on the behavior of the coupled system, most notably with its impact on resulting convection cells. Altering the depth ratio slightly can trigger a transition from full-convection where convection cells extent throughout the entire domain to fluid-dominated convection where cells occupy only the fluid region. With current interest surrounding superposed fluid-porous medium systems in numerous projects of industrial, environmental, and geophysical importance (oil recovery, carbon dioxide sequestration, contamination in sub-soil reservoirs, etc.), being able to predict the critical depth ratio where this convection shift occurs is particularly timely. Based on the critical Rayleigh numbers of the respective uncoupled domains, we propose a theory for predicting the depth ratio required for the transition from full- to fluid-dominated convection. We find good agreement between critical depth ratios predicted from our theory and actual values, especially in the small Darcy number limit. [Preview Abstract] |
Sunday, November 24, 2019 4:27PM - 4:40PM |
G38.00004: Optimization of Porous Medium Structure to Enhance Heat Transfer in Microchannel Mohammad Zargartalebi, Anne Benneker Local overheating is a significant barrier in the optimal performance of cutting-edge miniature electronic devices. A promising technique for heat removal is using porous medium embedded microchannel heat sinks (MCHS). This work focuses on heat transfer optimization in MCHS by using a layered heterogeneous porous medium represented via columns of different pin sizes, using the lattice Boltzmann method. A combination of qualitative analysis of flow dynamics, temperature profiles and quantitative analysis is presented. We find that heat transfer in the system is a strong function of flow characteristics which are significantly altered by heterogeneous porous media. These porous media result in superior heat transfer when compared to homogeneous media because of different flow patterns. Particle tracing studies are done to monitor the complex flow geometry responsible for heat transfer enhancement. Typically, improved heat transfer characteristics are accompanied by an increase in resistance to fluid flow. We show that, depending on the order of the different layers of the porous medium, the heat transfer can be increased while the fluid flow resistance is reduced, allowing for an optimization of the porous medium structure, which is unprecedented in previous MCHS studies. [Preview Abstract] |
Sunday, November 24, 2019 4:40PM - 4:53PM |
G38.00005: Experimental investigation on the scaling of convective dissolution in porous media Marco De Paoli, Mobin Alipour, Alfredo Soldati Porous media convection in Rayleigh-B\'enard-type configuration is of paramount importance in many industrial and environmental applications. However, the fundamental behavior of the dissolution flux and its dependence on the system parameters are not yet well understood: Simulations and experiments give opposite indications. In particular, the results of two-dimensional Darcy simulations suggest that the dissolution rate during the convection-dominated regime is constant, whereas Hele-Shaw experiments show that it exhibits a Rayleigh-dependent behavior. With the aid of a novel experimental setup, in which the geometrical properties of the Hele-Shaw cell are varied independently, we obtain accurate measurements of solute fluxes and explain the Rayleigh-dependent character of the dissolution rate observed in previous numerical and experimental studies. Finally, we observe that non-Darcian effects (e.g. mechanical dispersion) may influence the dissolution rate in Hele-Shaw flows and possibly lead to the mismatch between experimental and numerical results. [Preview Abstract] |
Sunday, November 24, 2019 4:53PM - 5:06PM |
G38.00006: Longitudinal heat conduction effects in a microchannel filled with a porous medium and subjected to a uniform heat flux. Ian Monsivais, Jose Lizardi, Federico Mendez The conjugate heat transfer between the walls of a microchannel and a fluid circulating inside is numerically studied. The microchannel is filled with an homogeneous porous medium and subjected to a uniform heat flux on the external walls of the microchannel. The governing equations are written in dimensionless form and basically, we show the existence of two dimensionless parameters that govern the problem: the Darcy number, Da, and the conjugate heat transfer parameter $\alpha_{\mathrm{c}}$/$\varepsilon _{\mathrm{h}}^{\mathrm{2}}$. The numerical predictions show that for $\alpha_{\mathrm{c}}$/$\varepsilon_{\mathrm{h}}^{\mathrm{2\thinspace }}$\textgreater \textgreater 1, the temperature of the fluid at each point of the microchannel is higher than in the case of $\alpha _{\mathrm{c}}$/$\varepsilon_{\mathrm{h}}^{\mathrm{2}}$ \textless \textless 1. These limits are well known as the thermally thin and thermally thick wall limits respectively. [Preview Abstract] |
Sunday, November 24, 2019 5:06PM - 5:19PM |
G38.00007: Experimental evaluation of thermal transport in partially-porous channel flow Shilpa Vijay, Mitul Luhar While convective heat transfer in channels completely filled with metal foams has been studied extensively, heat transfer in channels that are partially filled with porous foams is less well understood. Previous direct numerical simulations for partially porous channel flow indicate that large vortex structures enhance turbulent heat transfer at the porous medium-unobstructed flow interface. This project aims to experimentally investigate this interfacial thermal transport. The experimental setup involves commercially-available Aluminum foams attached to a heater block and placed in a forced convection arrangement adjacent to an unobstructed channel of equal height. Pressure drop and temperature measurements have been made across the porous section for bulk Reynolds number ranging from 800-3500. Particle Image Velocimetry (PIV) measurements made at a subset of these Reynolds numbers confirm the emergence of interfacial vortex structures in certain conditions. Currently, heat transfer performance in this system is evaluated via estimates of the Nusselt number and friction factor. Ultimately, the PIV dataset will be used to quantify the effect of the interfacial turbulent flow on thermal transport [Preview Abstract] |
Sunday, November 24, 2019 5:19PM - 5:32PM |
G38.00008: Simultaneous measurement of velocity and concentration fields in Hele-Shaw cell Mobin Alipour, Dr. Marco De Paoli, Alfredo Soldati Convective dissolution in porous media has a wide range of applications such as sea ice formations, evaporation from soil and geological carbon dioxide storage. While the wealth of computational studies has shed a light on some fundamental features of this flow, experimental techniques currently adopted do not allow an easy, simultaneous and accurate measurement of concentration and velocity fields and we aim precisely at this gap. In this work, we performed experiments in Hele-Shaw geometry and used an optical technique to obtain the solute concentration field. We propose a concentration-based velocity reconstruction (CVR) algorithm, i.e. a new method to reconstruct the velocity field from the solute concentration measurements. In particular, measurements of the concentration gradients are used to reconstruct the velocity field from the momentum transport equation. Effect of gap thickness and non-Darcian behavior of the flow are analyzed by means of both concentration and velocity observations of the fingers. We compare the CVR results with the velocity fields obtained via particle tracking velocimetry (PTV) measurements, giving the guidelines for future experimental works. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700