Bulletin of the American Physical Society
75th Annual Meeting of the Division of Fluid Dynamics
Volume 67, Number 19
Sunday–Tuesday, November 20–22, 2022; Indiana Convention Center, Indianapolis, Indiana.
Session A19: Non-Newtonian Flows: Theory and Modeling |
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Chair: Yongji Wang, Princeton University; Seyed Mohammad Taghavi, Associate Professor at Laval University Room: 206 |
Sunday, November 20, 2022 8:00AM - 8:13AM |
A19.00001: Discovery of ice shelf rheology via physics-informed neural network Yongji Wang, Charlie Cowen-Breen, Ching-Yao Lai Ice shelves are floating extension of grounded ice and play a crucial role in slowing ice discharge from ice sheet into the ocean. Due to its slender-body shape and large effective viscosity, 3-D ice shelf can be considered as a 2-D flow governed by the shallow-shelf approximation (SSA) equations. Accurate description of ice’s non-Newtonian rheologyis is critical for the prediction of ice discharge into the ocean. Lab experiment showed that ice exhibits a power lawrelationship between the stress and strain rate, known as Glen’s law, which has been applied to various ice models for decades. Yet, it was unclear if this laboratory-derived flow law capture the complex behaviors of glacier ice at the continental scale. Here, we leverage the availability of satellite data and deep learning to reveal the underlying rheology of glacial ice. We use physics-informed neural network, combining the shallow-shelf approximation equations with the ice velocity and thickness data measured from satellite, to infer the effective viscosity of ice shelves, which is otherwise difficult to directly measure. We found that the stress-strain rate relation of ice shelves varies between the compression and extension zone. In the compression zone, the rheology of ice exhibits transitions between different power-laws, consistent with lab experiments in Goldsby and Kohlstedt (2001). In the extensional zone, the ice shelf behaves as a perfect plastic. Our result yields new flow laws of ice shelves that are different from those commonly assumed in ice-sheet models, suggesting a need to reassess processes sensitive to ice rheology. |
Sunday, November 20, 2022 8:13AM - 8:26AM |
A19.00002: Channel flow of a viscoplastic fluid with the presence of a superhydrophobic wall Hossein Rahmani, Seyed Mohammad Taghavi Plane Poiseuille flow of a Bingham fluid in channels with a superhydrophobic (SH) groovy wall is studied, via semi-analytical and numerical simulations. The lower wall is the SH groovy wall, where air is trapped inside the grooves, assuming that the liquid/air interface remains flat while attached to the groove edges. At the liquid/air interface, the Bingham fluid slips over the SH wall, for modeling of which the Navier slip law is used. We consider a transverse flow configuration where the groove direction is normal to the flow stream. Perturbing the flow governing equations over the no-slip flow solution, employing the Fourier expansion method and then solving for the linear terms, we obtain a semi-analytical solution, allowing us to solve for the flow velocity profiles for different flow parameters. We also perform complementary numerical simulations, in order to verify the semi-analytical solution results and to gain further insights about the flow dynamics and regimes. We evaluate the effects of the key dimensionless flow parameters, i.e. the Reynolds (R), Bingham (B) and slip (b) numbers, the channel thickness (ell), and the slip area fraction (varphi), on the flow variables (such as the flow velocity and the effective slip length). |
Sunday, November 20, 2022 8:26AM - 8:39AM |
A19.00003: Motion of a Taylor bubble in a shear-thinning liquid Davide Picchi, Pietro Poesio This talk will focus on the motion of a gaseous Taylor bubble in a capillary tube. Although the dynamics of a bubble in a Newtonian liquid have been the subject of several studies since the seminal works of Taylor and Bretherton, the case where the fluid exhibits a shear-thinning behaviour is much less understood. To fill this gap, we derive a lubrication model in the film region to identify the scaling laws for the bubble speed and the film thickness as a function of the Ellis number and the degree of shear-thinning. Our model identifies a universal scaling law for the effective viscosity that accounts for the interplay of the zero-shear-rate and shear-thinning effects. After discussing the features of the front and rear menisci, we present an analysis of the recirculation vortexes ahead of the bubble. |
Sunday, November 20, 2022 8:39AM - 8:52AM |
A19.00004: Wall Slip Mechanism During Flow Startup of a Pipe Filled with Complex Fluid Exhibiting Yielding Behavior Aniruddha Sanyal, Lalit Kumar Wall slip during flow startup operation involving gelled fluids like polymers, emulsions, etc. is mostly overlooked during numerical analysis. Hence, one may potentially misinterpret the fluid mechanics associated with the gel’s degradation and its subsequent clearance from the pipeline. In our study, we decipher numerically that the wall-slip mechanism modifies the net rheology governing the gel degradation at the bulk of the pipeline. The wall slip causes faster initial pressure wave propagation across weakly compressible-based fully homogeneous gelled pipelines during the flow startup operation. At a later time, the effect of wall-slip alleviates, and the bulk deformation dominates the proceedings. The intuition of low gel deformation for the case of wall slip-induced flow (compared to the scenario of no-slip) during initial compressive pressure propagation is not true in our present study. This is also verified through local variations in flow velocity and strain near the wall. This outcome is consistent across various types of complex fluids like elasto-viscoplastic and shear-thinning fluids. The mathematical model used in this study successfully replicates features like thixotropy, strain-dependent yielding behavior, and slip-stick mechanism at the wall-fluid interface. |
Sunday, November 20, 2022 8:52AM - 9:05AM |
A19.00005: shear alignment and defect dynamics in three-dimensional lamellar mesophase. Arkaprava Pal, Viswanathan Kumaran
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Sunday, November 20, 2022 9:05AM - 9:18AM |
A19.00006: Lagrangian stretching and polymeric stress: unification of two disparate branches of continuum mechanics Manish Kumar, Jeffrey S Guasto, Arezoo M Ardekani Polymeric flows are common in industrial, biological, and natural processes ranging from enhanced oil recovery to drug delivery to biofilm transport. The stretching of polymeric chains induces large polymeric stress which controls the flow dynamics and transport in polymeric flows. However, the measurement of polymeric stress is challenging. The Lagrangian stretching field is an easily computed Lagrangian coherent structure (LCS) that represents the hidden skeleton of the flow and behaves as a strong transport barrier. We have theoretically obtained a general relationship between the polymeric stress and the stretching fields for weak flows and also extended it for special flows having strong kinematics. Further, we have numerically shown a strong correlation between the stress and stretching fields for complex geometries and chaotic flows. Thus, this work unifies two disparate branches of continuum mechanics and establishes a simple framework to determine the topology of polymeric stress using a readily measured velocity field. |
Sunday, November 20, 2022 9:18AM - 9:31AM |
A19.00007: Viscoplastic model of mountain building Elvinas Ribinskas, Jerome A Neufeld, Thomasina V Ball, Camilla E Penney Scraping and compression of sediments at convergent tectonic boundaries leads to formation of accretionary wedges. Analogue rheological models for these sediments offer insights into the forces governing the development of these mountain ranges. |
Sunday, November 20, 2022 9:31AM - 9:44AM Not Participating |
A19.00008: Viscoplastic blisters Thomasina V Ball, Neil J Balmforth Many problems involve the spreading of a viscous fluid underneath a surface skin or crust, such as the intrusion of magma into the crust, the formation of ordered wrinkle patterns to produce microfluidic devices, and the reopening of airways in biological fluid mechanics. A characteristic of these types of problems is that the spreading is controlled by the physics at the fluid front rather than a bulk similarity solution. This leads to a matching problem between a quasi-static interior blister and the behaviour of the peeling region at the front. |
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