Bulletin of the American Physical Society
70th Annual Meeting of the APS Division of Fluid Dynamics
Volume 62, Number 14
Sunday–Tuesday, November 19–21, 2017; Denver, Colorado
Session Q38: Porous Media Flows: Soft MediaPorous
|
Hide Abstracts |
Chair: Peichun Amy Tsai, University of Alberta Room: 304 |
Tuesday, November 21, 2017 12:50PM - 1:03PM |
Q38.00001: Capturing gas in soft granular media Chris MacMinn, Jeremy Lee, Feng Xu, Sungyon Lee Bubble migration through soft granular materials involves a strong coupling between the bubble dynamics and the deformation of the material. This process is relevant to a variety of natural and industrial systems, from fluidized-bed reactors to the migration and venting of biogenic gas in sediments. Here, we study this process experimentally by injecting air into a quasi-2D, liquid-saturated packing of soft particles and measuring the morphology of the bubbles as they invade and then rise due to buoyancy. By systematically varying the confining stress, we show that the competition between buoyancy, capillarity, and elasticity leads to complex bubble-migration dynamics that transition from fluidization to pathway opening to pore invasion, with a strong and surprising impact on the amount of air trapped in the system. [Preview Abstract] |
Tuesday, November 21, 2017 1:03PM - 1:16PM |
Q38.00002: Tissue expansion and fluid absorption by skin tissue following intradermal injections through hollow microneedles Pranav Shrestha, Boris Stoeber Hollow microneedles provide a promising alternative to conventional drug delivery techniques due to improved patient compliance and the dose sparing effect. The dynamics of fluid injected through hollow microneedles into skin, which is a heterogeneous and deformable porous medium, have not been investigated extensively in the past. We have introduced the use of Optical Coherence Tomography (OCT) for real-time visualization of fluid injections into excised porcine tissue. The results from ex-vivo experiments, including cross-sectional tissue images from OCT and pressure/flow-rate measurements, show a transient mode of high flow-rate into the tissue followed by a lower steady-state infusion rate. The injected fluid expands the underlying tissue and causes the external free surface of the skin to rise, forming a characteristic intradermal wheal. We have used OCT to visualize the evolution of tissue and free surface deformation, and advancement of the boundary between regions of expanding and stationary tissue. We will show the effect of different injection parameters such as fluid pressure, viscosity and microneedle retraction on the injected volume. [Preview Abstract] |
Tuesday, November 21, 2017 1:16PM - 1:29PM |
Q38.00003: Non-Newtonian Flow-Induced Deformation From Pressurized Cavities in Absorbing Porous Tissues Aftab Ahmed, Javed Siddique We investigate the behavior of a spherical cavity in a soft biological tissue modeled as a deformable porous material during an injection of non-Newtonian fluid that follows a power law model. Fluid flows into the neighboring tissue due to high cavity pressure where it is absorbed by capillaries and lymphatics at a rate proportional to the local pressure. Power law fluid pressure and displacement of solid in the tissue are computed as function of radial distance and time. Numerical solutions indicate that shear thickening fluids exhibit less fluid pressure and induce small solid deformation as compared to shear thinning fluids. The absorption in the biological tissue increases as a consequence of flow induced deformation for power law fluids. In most cases non-Newtonian results are compared with viscous fluid case to magnify the differences. [Preview Abstract] |
Tuesday, November 21, 2017 1:29PM - 1:42PM |
Q38.00004: From red cells to soft porous lubrication. Qianhong Wu, Zenghao Zhu, Rungun Nathan In this paper, we report a novel experimental study to examine the lubrication theory for highly compressible porous media (Feng {\&} Weinbaum, JFM, 422, 282, 2000), which was applied to the frictionless motion of red cells over the endothelial surface layer (ESL). The experimental setup consists of a running conveyer belt covered with a porous sheet, and an upper planar board, i.e. planing surface. The pore pressure generation was captured when the planing surface glides over the porous sheet. If the lateral leakage was eliminated, we found that the overall pore pressure's contribution to the total lift, f$_{\mathrm{air}}\approx $80{\%}, and the friction coefficient $\eta =$0.0981, when U$=$5 m/s, L$=$0.381 m, $\lambda =$h$_{\mathrm{2}}$/h$_{\mathrm{0}}=$1 and k$=$h$_{\mathrm{2}}$/h$_{\mathrm{1}}=$3, where U is the velocity of the conveyor belt; L is the planing surface length; h$_{\mathrm{0}}$, h$_{\mathrm{1}}$ and h$_{\mathrm{2}}$ are the undeformed, leading and trailing edge porous layer thickness, respectively. f$_{\mathrm{air}}$ increases with the increase in U, $\lambda $ and L, while decreases with the increase in k. $\eta $ decreases with the increase in f$_{\mathrm{air}}$. If lateral pressure leakage exists, the pore pressure generation is reduced by nearly 90{\%}. All the results agreed well with the theoretical predictions. The study here lays the foundation for applying soft porous media for new type of bearing with significantly reduced friction. [Preview Abstract] |
Tuesday, November 21, 2017 1:42PM - 1:55PM |
Q38.00005: Flow near the boundary of random soft porous media Zhenxing Wu, Parisa Mirbod Understanding the velocity profile at the interfacial region between the porous layer and the free flow could help to accurately predict the flow rate and momentum in a soft porous medium and would lead to the design of advanced and efficient engineering and technological applications. We experimentally studied the characteristics of flow over the boundary of random soft porous materials. A planar particle image velocimetry (PIV) technique was used to obtain the detailed slip velocity at the interface between the porous media and the free flow region. We found that the normalized slip velocity depends on the porosity and pore space of porous medium. It was also found that the depth of the screening length inside the porous material is of the order of the channel height, which is different from the Brinkman's prediction. Using our experimental measurements, we then examined a model for the laminar flow over and inside porous media. We also analyzed an equation to determine the permeability of random soft porous media. This study provided the very first detailed analysis of flow over and at the interface of various soft random porous media using PIV technique and a step forward in understanding and modeling of the flow over soft random porous media. [Preview Abstract] |
Tuesday, November 21, 2017 1:55PM - 2:08PM |
Q38.00006: Fluid-Driven Deformation of a Soft Porous Medium Tyler Lutz, Larry Wilen, John Wettlaufer Viscous drag forces resisting the flow of fluid through a soft porous medium are maintained by restoring forces associated with deformations in the solid matrix. We describe experimental measurements of the deformation of foam under a pressure-driven flow of water along a single axis. Image analysis techniques allow tracking of the foam displacement while pressure sensors allow measurement of the fluid pressure. Experiments are performed for a series of different pressure heads ranging from 10 to 90 psi, and the results are compared to theory. This work builds on previous measurements of the fluid-induced deformation of a bed of soft hydrogel spheres. Compared to the hydrogel system, foams have the advantage that the constituents of the porous medium do not rearrange during an experiment, but they have the disadvantage of having a high friction coefficient with any boundaries. We detail strategies to characterize and mitigate the effects of friction on the observed foam deformations. [Preview Abstract] |
Tuesday, November 21, 2017 2:08PM - 2:21PM |
Q38.00007: A soft porous drop in linear flows Yuan-Nan Young, Michael Miksis, Yoichiro Mori, Michael Shelley The cellular cytoplasm consists a viscous fluid filled with fibrous networks that also have their own dynamics. Such fluid-structure interactions have been modeled as a soft porous material immersed in a viscous fluid. In this talk we focus on the hydrodynamics of a viscous drop filled with soft porous material inside. Suspended in a Stokes flow, such a porous viscous drop is allowed to deform, both the drop interface and the porous structures inside. Special focus is on the deformation dynamics of both the porosity and the shape of the drop under simple flows such as a uniform streaming flow and linear flows. We examine the effects of flow boundary conditions at interface between the porous drop and the surrounding viscous fluid. We also examine the dynamics of a porous drop with active stress from the porous network. [Preview Abstract] |
Tuesday, November 21, 2017 2:21PM - 2:34PM |
Q38.00008: On the examination of Darcy permeability of soft fibrous porous media; New correlations. Zenghao Zhu, Qiuyun Wang, Qianhong Wu In this presentation, we report a novel experimental approach to investigate the compression-dependent Darcy permeability of soft porous media. Especially, we are proposing new correlations that describe the change of the permeability of random fibrous porous media as a function of its compression. A special device was developed that consisted of a rectangular flow channel with adjustable gap thickness ranging from 3 mm to 20 mm. Air was forced through the thin gap filled with testing fibrous materials. By measuring the flow rate and the pressure gradient, we have successfully obtained the Darcy permeability of different fibrous porous materials at different compression ratios. Theoretical or semi-empirical models have been compared with the experimental results, indicating various degrees of disagreement. The new correlations were then proposed which fit with experimental data very well. The study presented herein provides a useful approach to evaluate the change of the permeability of fibrous porous media as a function of its compression. It will be valuable for examining fluid flow in fibrous porous media where the permeability is difficult to be measured directly. This kind of porous media widely exists in biological systems. [Preview Abstract] |
Tuesday, November 21, 2017 2:34PM - 2:47PM |
Q38.00009: Translation by anisotropic peeling or fracturing in elastic media Zhong Zheng, John Lister, Jerome Neufeld The influence of rock anisotropy on the direction of hydraulic fracturing is an important open question. Two canonical systems have been proposed to investigate the fundamental aspects of such fluid-structure interaction problems: (i) Fluid injection and fracturing into an infinite elastic matrix (e.g., solid gelatin) and (ii) Fluid invasion and peeling beneath a deforming elastic sheet (e.g., bending plate). We investigate the second system and impose a non-uniform prewetting film thickness beneath the elastic sheet. We notice that while the bulk of the elastic sheet retains the static blister shape, a non-uniform prewetting film thickness can cause a horizontal translation of the blister. In particular, for a step jump in prewetting film thickness, asymptotic analysis indicates that, under constant fluid injection, the horizontal translation follows a $t^{7/17}$ time dependence in cartesian coordinates, and the prefactor of power-law translation depends on the ratio of the distinct prewetting film thicknesses on either side. We also provide numerical and experimental evidence demonstrating anisotropic blister evolution. This can be thought of as a model system for fluid-driven fracturing where the non-uniform prewetting film thickness mimics heterogeneity in material toughness. [Preview Abstract] |
Tuesday, November 21, 2017 2:47PM - 3:00PM |
Q38.00010: Spontaneous imbibition of an idealized deformable porous media Jean-Baptiste Charpentier, Laurent Bizet, Abdelghani Saouab The spontaneous imbibition of undeformable porous media has been widely studied. The temporal evolution of the fluid front position with time generally follows Washburn’s law ($x \propto t^{1/2} $) for a one-dimensional system. However, if a porous medium is deformable then its imbibition dynamic might be different and depends on the way it deforms. In this study the spontaneous imbibition of a system consisting of parallel flexible sheets irregularly spaced from one another is numerically investigated. Firstly, the case of a flexible sheet between two rigid walls was considered. The simulation results were analyzed in terms of imbibition duration, volume of fluid in the system and amplitude of the sheet displacements at the end of the imbibition. The influence of the boundary conditions, elasticity, dynamic contact angle, intensity of the gravity field and ratio of the sheet distance to both rigid walls were investigated. It was found that the boundary conditions greatly influence the imbibition dynamic. Secondly, some simulations were done including more parallel flexible sheets. These second series of simulations confirmed the crucial role of the boundary conditions on the imbibition dynamic and on the flexible sheets clustering. [Preview Abstract] |
Tuesday, November 21, 2017 3:00PM - 3:13PM |
Q38.00011: Swelling of static and evolving polymer networks during frontal photopolymerisation Matthew G. Hennessy, Alessandra Vitale, Joao T. Cabral, Omar K. Matar Frontal photopolymerisation (FPP) is a directional solidification process that converts monomer-rich liquid into crosslinked polymer solid by light exposure. Inherent to this process is the creation of an evolving polymer network that is exposed to a monomer bath. A combined theoretical and experimental investigation is performed to determine the conditions under which monomer from this bath can diffuse into the propagating polymer network and cause it to swell. First, the growth and swelling processes are decoupled by immersing pre-made polymer networks into monomer baths held at various temperatures. The experimental measurements of the network thickness are found to be in good agreement with theoretical predictions obtained from a nonlinear poroelastic model. FPP propagation experiments are then carried out under conditions that lead to swelling. Unexpectedly, for a fixed exposure time, swelling is found to increase with incident light intensity. The experimental data is well described by a novel FPP-poroelastic model accounting for the simultaneous growth and swelling of the polymer network. Moreover, the model provides key insights into the interfacial instabilities seen in experiments. [Preview Abstract] |
Tuesday, November 21, 2017 3:13PM - 3:26PM |
Q38.00012: Experimental Analysis of Flow-Induced Matrix Deformation on Deviation from Darcy's Law in Deformable Porous Media Benjamin Munro, Sid Becker When a viscous fluid flows through a deformable porous medium, the response of the matrix and the flow field is coupled. The flow of the fluid through the elastic media causes matrix deformation and conversely, deformation of the matrix affects the fluid field by altering pressure within the pores. This study concerns the effect of flow-induced matrix deformation on deviation from Darcy's law at low Reynolds numbers in a deformable porous medium. The experiments consist of a glycerol and water mixture driven through an isotropic elastic porous matrix by an externally applied pressure gradient. The method of elastic matrix manufacture allows for a particular control of the matrix parameters: elasticity and pore geometry. The coupled solid-fluid interaction is then observed in an experimental test rig which captures the global flow behaviour, matrix deformation, and the onset of deviation from Darcy's law at low Re. The experimental data is then compared against theoretical and computational models, and presented so that the results can be used for numerical validation. [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