Bulletin of the American Physical Society
69th Annual Meeting of the APS Division of Fluid Dynamics
Volume 61, Number 20
Sunday–Tuesday, November 20–22, 2016; Portland, Oregon
Session D40: Porous Media Flows: General |
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Chair: Arezoo Ardekani, Purdue University Room: Portland Ballroom 253-258-254-257 |
Sunday, November 20, 2016 2:57PM - 3:10PM |
D40.00001: Title: Spatial velocity fluctuations in flow through porous media Soroush Aramideh, Tianqi Guo, Pavlos P. Vlachos, Arezoo M. Ardekani Understanding the flow in porous media is of great importance and has direct impact on many processes in chemical and oil industries, fuel cell design, and filtration. In this work, we use direct numerical simulations (DNS) to examine the flow through variety of sphere packings with different levels of complexity and heterogeneity. DNS results are validated with velocity fields obtained via volumetric particle tracking velocimetry at high resolution. We show that flow in random close packing of spheres has unique statistical properties while the medium is random itself. Furthermore, we quantify the relationship between pore geometry and velocity fluctuations. [Preview Abstract] |
Sunday, November 20, 2016 3:10PM - 3:23PM |
D40.00002: Volumetric microscale particle tracking velocimetry (PTV) in porous media. Tianqi Guo, Soroush Aramideh, Arezoo M. Ardekani, Pavlos P. Vlachos The steady-state flow through refractive-index-matched glass bead microchannels is measured using microscopic particle tracking velocimetry ($\mu $PTV). A novel technique is developed to volumetrically reconstruct particles from oversampled two-dimensional microscopic images of fluorescent particles. Fast oversampling of the quasi-steady-state flow field in the lateral direction is realized by a nano-positioning piezo stage synchronized with a fast CMOS camera. Experiments at different Reynolds numbers are carried out for flows through a series of both monodispersed and bidispersed glass bead microchannels with various porosities. The obtained velocity fields at pore-scale (on the order of 10 $\mu $m) are compared with direct numerical simulations (DNS) conducted in the exact same geometries reconstructed from micro-CT scans of the glass bead microchannels. The developed experimental method would serve as a new approach for exploring the flow physics at pore-scale in porous media, and also provide benchmark measurements for validation of numerical simulations. [Preview Abstract] |
Sunday, November 20, 2016 3:23PM - 3:36PM |
D40.00003: Morse-Smale spectra reveal topological phase transition in porous media flow Norbert Stoop, Nicolas Waisbord, Vasily Kantsler, Jeffrey S. Guasto, Joern Dunkel We introduce spectral Morse-Smale analysis to identify topological phase transitions in disordered continuous media. Combining microfluidic experiments with large-scale, pore-resolved simulations of porous media flow, we demonstrate that invariants of Morse-Smale graphs of flow speed provide a well-defined measure of the effects of spatial disorder on fluid transport. By systematically perturbing a microfluidic lattice, the fluid flow topology undergoes a phase transition from periodic to filamentous flow structure, which corresponds to a change in the spectral density of the Morse-Smale graphs and carries important implications for advective transport and front dispersion. Due to its generic formulation, the proposed spectral Morse-Smale analysis can be extended to characterize topological transformations in physical, chemical or biological continuum systems. [Preview Abstract] |
Sunday, November 20, 2016 3:36PM - 3:49PM |
D40.00004: Preferential paths in yield stress fluid flow through a porous medium Jeffrey Guasto, Nicolas Waisbord, Norbert Stoop, J{\"o}rn Dunkel A broad range of biological, geological, and industrial materials with complex rheological properties are subjected to flow through porous media in applications ranging from oil recovery to food manufacturing. In this experimental study, we examine the flow of a model yield stress fluid (Carbopol micro-gel) through a quasi-2D porous medium, fabricated in a microfluidic channel. The flow is driven by applying a precisely-controlled pressure gradient and measured by particle tracking velocimetry, and our observations are complemented by a pore-network model of the yield stress fluid flow. While remaining unyielded at small applied pressure, the micro-gel begins to yield at a critical pressure gradient, exhibiting a single preferential flow path that percolates through the porous medium. As the applied pressure gradient increases, we observe a subsequent coarsening and invasion of the yielded, fluidized network. An examination of both the yielded network topology and pore-scale flow reveal that two cooperative phenomena are involved in sculpting the preferential flow paths: (1) the geometry of the porous microstructure, and (2) the adhesive surface interactions between the micro-gel and substrate. [Preview Abstract] |
Sunday, November 20, 2016 3:49PM - 4:02PM |
D40.00005: Simulation of incompressible two-phase flow in porous media with large timesteps Daniel Cogswell, Michael Szulczewski Simulations of flow in porous media suffer from severe timestep restrictions as the permeability and viscosity contrast become increasingly heterogeneous, even when solved with a fully implicit discretization. Previous efforts to alleviate these restrictions have focused on numerical methods, but the problem persists because it originates from the shape of the fractional flow function. Here we focus on regularizing the equations themselves with the addition of an energy constraint. The equations for the flow of two immiscible, incompressible fluid phases in porous media are recast as a gradient flow using the phase-field method, a macroscopic surface tension is introduced, and a convex energy splitting scheme is applied to enable unconditionally large timesteps. Using the phase-field formulation as a homotopy map, the unmodified flow equations can be solved with large timesteps, even with high degrees of heterogeneity in permeability and viscosity. For a 2D test problem, the homotopy method allows the timestep to be increased by more than four orders of magnitude relative to the unmodified equations. [Preview Abstract] |
Sunday, November 20, 2016 4:02PM - 4:15PM |
D40.00006: Dispersive effects on the multi-layer porous media flows with permeable and impermeable interfaces Prabir Daripa, Craig Gin We investigate dispersive effects on the linear stability of multi-layer porous media flow models of enhanced oil recovery for two different types of interfaces: permeable and impermeable interfaces. Results presented are relevant for the design of smarter interfaces in the available parameter space of Capillary number, Peclet number, longitudinal and transverse dispersion and the viscous profile of the middle layer. The stabilization capacity of each of these two interfaces is explored numerically and conditions for complete dispersive stabilization are identified for each of these two types of interfaces. Several key results will be presented including our finding that for most values of the flow parameters, permeable interfaces suppress flow instability more than impermeable interfaces. Time permitting, full simulation results will also be presented. [Preview Abstract] |
Sunday, November 20, 2016 4:15PM - 4:28PM |
D40.00007: Diffuse-Interface Modelling of Flow in Porous Media Doug Addy, Marc Pradas, Marcus Schmuck, Serafim Kalliadasis Multiphase flows are ubiquitous in a wide spectrum of scientific and engineering applications, and their computational modelling often poses many challenges associated with the presence of free boundaries and interfaces. Interfacial flows in porous media encounter additional challenges and complexities due to their inherently multiscale behaviour. Here we investigate the dynamics of interfaces in porous media using an effective convective Cahn-Hilliard (CH) equation recently developed in [1] from a Stokes-CH equation for microscopic heterogeneous domains by means of a homogenization methodology, where the microscopic details are taken into account as effective tensor coefficients which are given by a Poisson equation. The equations are decoupled under appropriate assumptions and solved in series using a classic finite-element formulation with the open-source software FEniCS. We investigate the effects of different microscopic geometries, including periodic and non-periodic, at the bulk fluid flow, and find that our model is able to describe the effective macroscopic behaviour without the need to resolve the microscopic details. [1] M. Schmuck, M. Pradas, G.A. Pavliotis and S. Kalliadasis, 2013, Nonlinearity {\bf 26} 3259-3277. [Preview Abstract] |
Sunday, November 20, 2016 4:28PM - 4:41PM |
D40.00008: Modeling and Simulations of Particulate Flows through Functionalized Porous Media Chunhui LI, Prashanta Dutta, Jin Liu Transport of particulate fluid through a functionalized porous material is of significant interest in many industrial applications, such as earth sciences, battery designs and water/air purifications. The entire process is complex, which involves the convection of fluid, diffusion of reactants as well as reversible chemical reactions at the fluid-solid interface In this work we present a convection-diffusion-reaction model and simulate the transport of particulate fluid through a functionalized porous media. The porous structures are generated and manipulated through the quartet structure generation set method. The Navier-Stokes with convection-diffusion equations are solved using the lattice Boltzmann method. The chemical reactions at the interface are modeled by an absorption-desorption process and treated as the boundary conditions for above governing equations. Through our simulations we study the effects of porous structures, including porosity, pore orientation, and pore size as well as the kinetic rates of surface reactions on the overall performance of removal efficiency of the species from the solution. Our results show that whole process is highly affected by both the porous structures and absorption rate. The optimal parameters can be achieved by proper design. [Preview Abstract] |
Sunday, November 20, 2016 4:41PM - 4:54PM |
D40.00009: Diffusion in random networks: Asymptotic properties, and numerical and engineering approximations Juan C. Padrino, Duan Z. Zhang The ensemble phase averaging technique is applied to model mass transport by diffusion in random networks. The system consists of an ensemble of random networks, where each network is made of a set of pockets connected by tortuous channels. Inside a channel, we assume that fluid transport is governed by the one-dimensional diffusion equation. Mass balance leads to an integro-differential equation for the pores mass density. The so-called dual porosity model is found to be equivalent to the leading order approximation of the integration kernel when the diffusion time scale inside the channels is small compared to the macroscopic time scale. As a test problem, we consider the one-dimensional mass diffusion in a semi-infinite domain, whose solution is sought numerically. Because of the required time to establish the linear concentration profile inside a channel, for early times the similarity variable is \textit{xt}$^{\mathrm{-1/4}}$ rather than \textit{xt}$^{\mathrm{-1/2}}$ as in the traditional theory. This early time sub-diffusive similarity can be explained by random walk theory through the network. In addition, by applying concepts of fractional calculus, we show that, for small time, the governing equation reduces to a fractional diffusion equation with known solution. We recast this solution in terms of special functions easier to compute. Comparison of the numerical and exact solutions shows excellent agreement. [Preview Abstract] |
Sunday, November 20, 2016 4:54PM - 5:07PM |
D40.00010: Influence of the multiphase flow patterns on the transport properties Bojan Markicevic The capillary network model with the dynamic boundary condition at free interface for displacement flow in porous media is developed, in which the net flow into each pore at the free interface can be less, equal to or greater than zero. The spread of the liquid and form of the liquid flow patterns are resolved in the networks of different sizes and heterogeneity and for two types of the boundary conditions, the constant inlet pressure or constant flow rate. It has been shown that for the constant flow rate boundary condition, the pressure drop throughout the network remains constant due to the pressure increase at the inlet boundary. The constant pressure drop produces the similar flow patterns during the displacement flow, and the saturation remains constant in the flow direction. The liquid saturation in the network is varied gradually by increasing the liquid flow rate at network inlet. For each distinct flow rate, the sizes of the repeating flow pattern and corresponding pressure drop change accordingly. This implies that for sufficiently large networks in which the flow pattern is fully developed, the transport parameters do not depend on the network size. The flow pattern and transport parameters depend on the network heterogeneity, as the dynamic boundary condition changes at the free interface producing a different distribution of the liquid. A continuous development of the flow pattern is also observed for the constant inlet pressure boundary condition, where the pressure drop decreases as liquid advances into the network. Finally, a summary in changes of transport parameters, relative permeability and capillary pressure, is elaborated. [Preview Abstract] |
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