Bulletin of the American Physical Society
APS March Meeting 2024
Monday–Friday, March 4–8, 2024; Minneapolis & Virtual
Session M34: Soft and Living Matter in Geophysical FlowsFocus
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Sponsoring Units: DSOFT GPC DBIO DFD Chair: Amir Pahlavan, Yale Room: 102F |
Wednesday, March 6, 2024 8:00AM - 8:36AM |
M34.00001: Cooperative transport of emulsions in porous media Invited Speaker: Shima Parsa Transport of soft and deformable materials in confinement is ubiquitous in geological flow. As an example, the transport and retention of individual dispersed fluid blobs in porous media has been explored from the perspective of the balance between capillary and viscous forces at the interfaces of fluids. However, the network connectivity, interfacial interactions, and cooperative transport of a dispersed phase are not reflected in the transport models of fluids. Here, we investigate the transport of emulsions in a micromodel of porous medium using microfluidics and optical imaging. By varying the size, concentration, and injection rate of the emulsions we observe that large and deformable emulsions are essential in the mobilization of small and trapped emulsions. In contrast with the bulk transport measurements, our pore-level transport data indicates that emulsions are more likely to be mobilized due to clogging of neighboring pores than single droplet transport. |
Wednesday, March 6, 2024 8:36AM - 9:12AM |
M34.00002: Active matter transport in porous mediums Invited Speaker: Arshad Kudrolli Many organisms including bacteria, nematodes, and vertebrates, spanning in length from microns to meters, can be found in porous fluid-saturated mediums ranging from tissue to granular beds. Depending on their relative size, such active matter may move entirely within the pore space or rearrange the material locally, depending on the topology and strength of the medium. There is considerable interest in understanding the strategies employed in achieving transport, towards applications in robotics, oil recovery, logic design in microfluidic devices, and high-throughput motility-based sorters. We shall discuss a series of studies with Lumbriculus variegatus, also known as California blackworms, as they move through model porous medium in the form of transparent index matched granular hydrogels, or laser-cut mazes consisting of chambers connected by narrow passages. These slender limbless worms perform undulatory and peristaltic strokes and use their head to actively probe their surroundings. We will show how the worm employs the different strokes to move through the medium, which changes character with increasing overburden pressure. The importance of boundary following and body strokes in determining how active matter escapes from enclosed spaces will be highlighted in the limit where the interaction with the solid component of the medium is steric. We will discuss active polymer models and the degree to which they can capture the trapping and diffusion statistics of the worm. Finally, we will address questions on the influence of activity as it relates to the entanglement of these filamentary worms and clogging while they move through narrow passages. |
Wednesday, March 6, 2024 9:12AM - 9:24AM |
M34.00003: Foam Transport in Porous Media Sibani Lisa Biswal, Yiwei Wang Foams are essential in a variety of geophysical systems such as enhanced oil recovery, environmental remediation, to subsurface carbon dioxide sequestration. Thus, there is a need to understand the fundamental physicochemical processes associated with foam to predict its behavior in geological environments. Microfluidics have been proven effective in visualizing small-scale events and processes that would otherwise be difficult to observe in natural confined systems. Here, a microfluidic device designed to mimic natural heterogeneous sandstone porous media is employed to investigate the effects of gas types on gas trapping, foam texture, foam stability, and phase mobility in quasi-steady-state flowing foam. Phenomena such as foam bubble trapping and lamellae division will be compared. |
Wednesday, March 6, 2024 9:24AM - 9:36AM |
M34.00004: Phoretic Delivery of Colloids to Biofilms in Complex Environments Zehao Chen, Amir Pahlavan Bacterial infections are notoriously challenging to treat due to the biofilm extracellular polymer matrix's ability to limit the diffusion and penetration of drugs. We present an effective approach to enhance nanoparticle penetration into biofilms formed in complex environments. Utilizing microfluidic experiments, we demonstrate that phoretic migration due to imposed solute gradients can be harnessed to deliver colloidal particles into the biofilm matrix. This technique holds promise for targeted treatment of bacterial infections in confined, and tortuous environments such as skin, intestine, or medical implants. |
Wednesday, March 6, 2024 9:36AM - 9:48AM |
M34.00005: Barriers, chutes and long-range transport of active tracers in vortex flows Thomas H Solomon, Nghia Le We present experiments on the effects of imposed, two-dimensional, laminar flows on the motion of self-propelled tracers. The self-propelled particles are motile algae microbes (tetraselmis and euglena) or brine shrimp (artemia) nauplii, and the flow is a time-independent chain or array of vortices, driven magnetohydrodynamically. The trajectories of the swimming organisms in the flows are analyzed in terms of a theory of "swimming invariant manifolds" (SwIMs). These SwIMs separate trajectories into distinct regions in a three-dimensional phase space determined by the x and y coordinates and swimming directions of the microbes. Projected into physical, x-y space, the edges of the SwIMs act as one-way barriers through which the active tracers can cross in one-direction only. This theory is a generalization of a theory of "burning invariant manifolds" (BIMs) that have previously been shown to act as one-way barriers that block the motion of propagating reaction fronts in laminar flows. The SwIMs also combine to produce "chutes" that carry microbes between adjacent vortices. We measure the growing variance of an ensemble for different microbe swimming speeds and interpret those results in terms of the SwIM geometry and the coexistence of ordered and chaotic trajectories of the swimming microbes. |
Wednesday, March 6, 2024 9:48AM - 10:00AM |
M34.00006: The dynamics of swimmers in vortex-dominated flows: the role of rotational noise Kevin A Mitchell, Taylor J Whitney, Thomas H Solomon We use dynamical systems techniques to study the transport of swimming microorganisms, such as the marine algae tetraselmis, in vortex-dominated, two-dimensional flows. In particular, we analyze so-called "invariant tori" in phase space that result in tubes generating long-range ballistic transport along the separatrices between vortices. Particular attention is focused on the impact of rotational stochasticity on the robustness of these tori. We first extract a noise model directly from experimental trajectories of algae in a laboratory sheer flow. This model turns out to be non-Gaussian, with a Lorentzian probability distribution. This rotational noise is then combined with the deterministic swimmer dynamics. The impact of noise on the root-mean-square and maximum distance attained is studied as a function of swimmer shape and swimming speed. |
Wednesday, March 6, 2024 10:00AM - 10:12AM |
M34.00007: Life of Cyanobacteria in Turbulent Lakes Yuri Sinzato, Robert Uittenbogaard, Petra Visser, Jef Huisman, Maziyar Jalaal Forming and maintaining large colonial structures is essential for the success of bloom-forming cyanobacteria. Yet, the influence of the lake hydrodynamics in the modulation of the colony size is not well understood. We investigate how fluid flow results in aggregation and fragmentation of cyanobacterial colonies. Laboratory cell cultures are subjected to shear at the inertial regime, and the time evolution of the colony size distribution is measured with direct imaging of the suspension. A numerical model based on non-linear population dynamics describes the measured size distribution. Finally, we categorize the flow conditions in which cell fragmentation and aggregation are relevant at various geophysical flow conditions. |
Wednesday, March 6, 2024 10:12AM - 10:24AM |
M34.00008: Microbe-fluid-sediment interactions in aquatic and terrestrial ecosystems Judy Yang A wide variety of global environmental and health issues involve physical and biological interactions among fluids, particles or surfaces, and microbes at both micro- and macro-scales. For example, macro- or channel-scale sediment transport, a key process that controls coastal erosion, can vary by several orders of magnitude due to micro-scale sediment-sediment and sediment-bacteria interactions, including aggregation and biofilm formation. Other examples include clay algae flocculation, one of the most promising methods to remove harmful algal blooms, and soil carbon storage, responsible for the uptake of about 20% of annual anthropogenic carbon emissions, both of which are strongly impacted by the physical and biogeochemical interactions between particles and microbes at the micro-scale. Experimental studies of fluid-particle/surface-bacteria interactions across both micro- and macro-scales are needed to address these issues, yet such experiments are currently lacking. In this talk, I will discuss how I use flume experiments to study sediment transport, microfluidic experiments to study soil carbon dynamics, and meso-scale microbial experiments to study bacterial spreading in soil. Afterward, I will discuss how my group is integrating technologies at different scales to develop fundamental understanding of biota-particle-fluid interactions to address the above global issues. |
Wednesday, March 6, 2024 10:24AM - 10:36AM |
M34.00009: Aerobiology with Acoustic Levitation Derrick Rodriguez, Ranjiangshang Ran, Schuyler Arn, Keiran Stevenson, Minsu Kim, Josef Dufek, Joshua Mendez Harper, Justin C Burton Airborne microbes critically impact our everyday lives, e.g., rainfall, disease spread, land fertilization, and food production. Often these microbes hitchhike on particulates – often referred to as bioparticulates – which can remain suspended in the atmosphere and undergo intercontinental transits. Detailed laboratory studies of airborne microbiota are essential for understanding Earth's ecosystems, yet current studies mostly dwell on soil/marine microbiota. Acoustic levitation is one possible route to investigating airborne microbes in the lab by imitating atmospheric conditions and testing different particulates without physical contact. With this goal in mind, we investigated various designs of acoustic levitators to optimize acoustic trapping forces while remaining cost-effective and scalable. Utilizing an array of ultrasonic transducers roughly based on the TinyLev design, we levitated materials of different densities such as polystyrene, volcanic pumice, glass, water, and light metals. Furthermore, we test the performance of our acoustic levitators in different environmental conditions by varying the humidity, temperature, pressure, and other physical conditions relevant to the mechanics of airborne particles. These results will be useful in understanding the survival of airborne microorganisms in the troposphere. |
Wednesday, March 6, 2024 10:36AM - 10:48AM |
M34.00010: Submerged cohesive granular collapse: Influence of packing density Eckart Meiburg, Rui Zhu We explore the submerged collapse of cohesive granular columns, as a function of packing density and cohesive force strength, via grain-resolving direct numerical simulations. We investigate both randomly packed granular columns as well as densely packed columns with an initial hexagonal close-packed (HCP) structure. The cohesive force acts to reduce the final runout distance of the collapsing column, and it entirely prevents the collapse when it exceeds a critical value. This critical value decreases with increasing packing density. The collapsing column has distinct failure planes, whose angle with the horizontal increases with the packing density. A force-chain network analysis indicates that strong cohesive force chains form more easily in the failure region and have a larger size as the cohesive force and packing density increase, which induces a larger macroscopic cohesive resistance. The cohesive force significantly accelerates the contraction of loosely packed columns and decelerates the dilation of densely packed columns, resulting in a more complex evolution of the local porosity and pore pressure. |
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