Bulletin of the American Physical Society
77th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 24–26, 2024; Salt Lake City, Utah
Session A20: Non-Newtonian Flows I: General |
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Chair: Neil Balmforth, University of British Columbia Room: 250 D |
Sunday, November 24, 2024 8:00AM - 8:13AM |
A20.00001: Transport of a Temperature-Responsive Microgel in a Hele-Shaw Cell: Jamming at Low Temperatures for Geothermal Applications Adam Jacob Hawkins, Aaron Baxter, Danni Tang, Vanessa R Kern, Patrick Fulton, Jefferson W Tester, Ulrich Wiesner, Sarah Hormozi Commercially-successful geothermal systems require balance between thermal and hydraulic performance. An injector-producer well pair with exceptional hydraulic performance, for instance, may have inadequate thermal performance if the effective heat transfer surface area is insufficient. In such a circumstance the current state-of-the-art is to abandon such well pairs once production well temperatures fall below design/operating criteria. Here, a temperature-responsive microgel is introduced as a novel solution that enables cooled “short circuits” to be sealed off and circulating fluids to be redirected to hotter flow paths. By employing a counter-intuitive volume-phase transition, this treatment increases the effective heat transfer area and subsequently improves heat transfer efficiency by increasing production well temperatures. Bench-scale laboratory experiments are presented and the anticipated improvement to thermal performance is determined from a hypothetical case. |
Sunday, November 24, 2024 8:13AM - 8:26AM |
A20.00002: Numerical Simulation of Phase Distribution in Recycled Immiscible Polymer Blends Hamideh Rouhanitazangi, jiacai Lu, Gretar Tryggvason Understanding phase distribution in immiscible polymer blends is crucial for enhancing material properties, especially with recycled polyethylene (PE) and isotactic polypropylene (iPP). Our study examines phase distribution under various flow conditions using numerical simulations with the Navier-Stokes equation and the Oldroyd-B fluid model, combined with a finite volume-front tracking method. We analyze phase distribution in pressure-driven flow with varying volume fractions. Results show that low volume fractions form drops in the continuous phase, while comparable fractions result in a co-continuous structure. In pressure-driven parallel flow, the mixture forms a film of the continuous phase near the walls, maintaining a uniform distribution in the bulk. The average velocity profile for different Weissenberg numbers (Wi) indicates that intermediate Wi values reduce the flow rate compared to Newtonian and high Wi flows. These findings highlight the impact of volume fraction and viscosity contrast on phase distribution. Future research will incorporate temperature dependence to study cooling and solidification, guiding the design of higher-quality recycled polymer blends for more sustainable and efficient material usage. |
Sunday, November 24, 2024 8:26AM - 8:39AM |
A20.00003: Plastic Failure Modes of Rectangles, Triangles and Drums Jiyuan Dai, Neil J Balmforth, Duncan R Hewitt A block of yield-stress fluid fails under gravity when its surface becomes too steep. In this study we examine the modes of failure of rectangular and triangular blocks leaning against a vertical wall,and of a partially filled cylindrical drum. |
Sunday, November 24, 2024 8:39AM - 8:52AM |
A20.00004: Influence of viscoelasticity in the flow on 1DOF and 2DOF vortex-induced vibrations of a cylinder Umang N. Patel, Jonathan P Rothstein, Yahya Modarres-Sadeghi We perform CFD simulations to study vortex-induced vibrations (VIV) of a cylinder in the inertial-elastic flow at a Reynolds number of Re = 100 and for a range of Weissenberg numbers of 0 < Wi < 10. In this range of Reynolds and Weissenberg numbers, both inertia and elasticity of the flow must be considered when it interacts with a flexibly-mounted cylinder. We use the FENE-P model to describe the viscoelastic fluid and investigate the effects of the Weissenberg number and the maximum polymer extensibility on the response of a flexibly-mounted cylinder with one or two degrees of freedom placed in flow. In addition to the primary vortices, we observe secondary vortices in the wake that are formed due to viscoelasticity in the flow. For increased elasticity in the fluid, we observe significant polymer deformation in the upstream stagnation region resulting in a region of large elastic stress that acts as a wall around the cylinder. As a result, the stagnation point moves upstream of the cylinder creating a finite gap between the shear layers and the cylinder surface. The region of flow separation is both widened and extended further downstream. With increased elasticity, VIV is suppressed in both one- and two-degree-of-freedom cases. We show that higher harmonic forces that are typically observed for the two-degree-of-freedom VIV responses in a Newtonian flow and cause increased fatigue damage in the structure, are suppressed by adding elasticity to the flow. |
Sunday, November 24, 2024 8:52AM - 9:05AM |
A20.00005: Viscoelastic friction reduction in the infinite length journal bearing Jonathon K Schuh Viscoelastic fluids in shear produce normal stresses. In rotating devices, these normal stresses produce a non-zero pressure field that would not exist in the same flow conditions with purely viscous fluids. This additional elastic pressure field has been used to increase the load carrying capacity and decrease the coefficient of friction in thrust bearings, and that same analysis can be extended to journal bearings. Here, the Cauchy momentum equations in polar coordinates are solved in the thin film limit using a perturbation expansion in the Deborah number (De) for both velocity and pressure. Viscoelasticity is included through an Upper Convected Maxwell model with a solvent viscosity (Upper Convected Jeffreys model). When De=0, the model resembles the Reynolds equation (a restatement of conservation of mass and momentum for a purely viscous fluid) for an infinite length journal bearing. The De=0 results match the predictions of the Reynolds equation over all eccentricity ratios, validating the model. As the De increases, the elastic contributions to the pressure and velocity fields increase the load carrying capacity and decrease the coefficient of friction compared to the results with the purely viscous fluid in the same flow conditions. This suggests that viscoelasticity is beneficial in journal bearing applications and provides designers another mechanism for decreasing friction in lubricated journal bearings. |
Sunday, November 24, 2024 9:05AM - 9:18AM |
A20.00006: Abstract Withdrawn
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Sunday, November 24, 2024 9:18AM - 9:31AM |
A20.00007: Transient Dynamics of the Rod-Climbing Effect in Oldroyd-B Fluids Tachin Ruangkriengsin, Rodolfo Brandao Macena Lira, Jonghyun Hwang, Katie Wu, Howard A Stone The Weissenberg effect, or rod-climbing phenomenon, occurs in non-Newtonian fluids where the fluid interface ascends along a rotating rod. Despite its prominence, theoretical insights into this phenomenon remain limited. In earlier work, D.D. Joseph and R. L. Fosdick (Arch. Ration. Mech. Anal., 1973); see also More et al. (Soft Matter, 2023), employed domain perturbation methods for second-order fluids to determine the equilibrium interface height by expanding solutions based on the rotation speed. Here, we investigate the time-dependent interface height by examining the interplay between gravity and viscoelasticity, while neglecting surface tension and inertia effects. We conduct our theoretical analysis using dimensionless quantities and derive equations from the Oldroyd-B model. By focusing on the small-deformation scenario, we obtain an analytical solution for the time-varying height that depends on the Weissenberg number and a dimensionless gravity parameter. |
Sunday, November 24, 2024 9:31AM - 9:44AM |
A20.00008: Pressure drop reduction of shear-thinning fluids in weakly deformable channels via the Lorentz reciprocal theorem Shrihari D Pande, Ivan C. Christov We employ the Lorentz reciprocal theorem to derive a closed-form expression for the pressure drop reduction due to the coupling between shear-thinning fluid flow and a weakly deformable channel wall. The reciprocity relation is obtained for a generalized Newtonian fluid whose effective viscosity is a function of shear stress. Importantly, our approach does not assume any restriction on the non-Newtonian correction being "small" or "weak'' (such as a low Carreau number). The only limitation of the approach is that the viscosity model must allow for a closed-form solution for the axial velocity profile in a straight and rigid channel. As a featured example, we consider the Ellis viscosity model, which captures the incipience of shear thinning. The analytical expression for the pressure drop reduction obtained via the reciprocal theorem under the Ellis model allows us to recover the Newtonian case (resp. the power-law regime) for small (resp. large) Carreau number or, equivalently, large (resp. small) Ellis number, as special cases. The approach based on the Lorentz reciprocal theorem offers the possibility of calculating the pressure drop of non-Newtonian fluid flows in deformable channels without solving a coupled elastohydrodynamics problem. |
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