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 R22: Particle-Laden Flows: Theory and Modeling I |
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Chair: Jesse Capecelatro, University of Michigan Room: 250 F |
Monday, November 25, 2024 1:50PM - 2:03PM |
R22.00001: A filtered coarse-grain Euler-Lagrange formulation for simulating fluidized polydisperse particles Sathvik Bhat, Yuan Yao, Pedram Pakseresht, Yi Fan, Jorg Theuerkauf, Jesse S Capecelatro Coarse-grain simulations of particle-laden flows to industrially relevant scales are unable to account for every particle in the system. A common approach to reduce the computational cost is to lump particles into parcels. Ad-hoc corrections are often employed to counter the effects of coarse-grain approximations. They typically fail to converge to the underlying deterministic equations in the limit the number of particles within the parcel approaches unity. In this work, a rigorous formulation of the filtered Eulerian-Lagrangian equations are presented. While exact, the equations result in unclosed terms, notably a sub-filtered drag force. Parcel collisions are handled using soft-sphere approach, modifying the coefficient of restitution based on the number of particles per parcel. The unclosed terms are informed by highly resolved (deterministic) Euler-Lagrange simulations of unbounded moderately dense gas-solid flows. Variation in particle size and velocity within each parcel is quantified. The relative contribution of the sub-filtered drag is found to increase with the number of particles per parcel, and depend on the local filtered volume fraction and Reynolds number. Symbolic regression is employed to obtain closed-form algebraic models. |
Monday, November 25, 2024 2:03PM - 2:16PM |
R22.00002: Development of an experimentally-validated analytical framework to study particle-laden flows for biomedical regimes Ahmed Paridie, Omid Amili In this work, an analytical framework is developed to describe the motion of a single particle or a system of particles within an unsteady, non-uniform, incompressible flow, focusing on rigid spheres translating in Newtonian fluids in two-way and four-way coupled regimes. The study aims to formulate particle motion using force terms that are more inclusive and general, yet theoretically feasible. For example, the non-linear fluid forces due to the convective term in the Navier-Stokes equation are obtained analytically. In addition, theoretical formulations for the coupling forces between particles and the resulting velocity field are developed. Both steady-state and transient portions of the forces are calculated. The regions where coupling force fields are significant with respect to chosen thresholds will be quantified. Additionally, these force fields will be used in a time-marching module to demonstrate the motion of particles and the resulting disturbed flow field in two-way coupled regimes. These formulations are validated against a variety of experimental test cases in both Eulerian and Lagrangian frameworks, using measurements from image-based methods such as particle image velocimetry (PIV) and particle tracking velocimetry (PTV). |
Monday, November 25, 2024 2:16PM - 2:29PM |
R22.00003: Abstract Withdrawn
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Monday, November 25, 2024 2:29PM - 2:42PM |
R22.00004: Phase interaction force model for nonuniform particle laden flows Duan Zhong Zhang, Min Wang, S Balachandar Many models for phase interaction forces, such as drag, are developed in statistically homogeneous flows, while most multiphase flows in nature or in engineering applications are inhomogeneous. This work studies the corrections to the drag model considering effect of statistical inhomogeneity. Let L be the macroscopic length scale. If there is any effect of the inhomogeneity on the phase interaction force, the force should be a function of L, implying that force model cannot be developed by only studying the average forces in homogeneous flows, since such flows contain no information about L. |
Monday, November 25, 2024 2:42PM - 2:55PM |
R22.00005: Impact of Particle Volume Fraction Gradient on Particle-Fluid Phase Interaction Models Min Wang, Duan Zhong Zhang, S Balachandar Phase interaction forces are crucial in modeling multiphase flows. Most existing models have been developed based on statistically homogeneous flows, even though most practical flows are inhomogeneous. This study examines the effects of particle volume fraction gradients on fluid-particle interactions through numerical simulations of flows passing through fixed arrays of particles with volume fraction gradients. Both uniform and non-uniform particle volume fractions are analyzed and compared for disperse multiphase flows, with particle Reynolds numbers ranging from 1 to 100 and particle volume fractions ranging from 1% to 26% in statistically steady states. |
Monday, November 25, 2024 2:55PM - 3:08PM |
R22.00006: Chaotic Behaviour of Mutliple Immersed Ellipsoids Andrew Boyd, Mark Sawyer, David Scott, Rama Govindarajan, Prashant Valluri
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Monday, November 25, 2024 3:08PM - 3:21PM |
R22.00007: A Force Correction Scheme for Volume Filtered Large Eddy Simulation of Flow Over a Permeable Bed of Particles Daniel Fust, S Balachandar, Sourabh V Apte A volume filtered formulation (Whitaker 1996) for large eddy simulation of flow over a bed of randomly packed particles, with size on the order of 10 wall units, is investigated. Volume filtering across the fluid-particle interface results in bed-normal porosity variation with unit porosity in the freestream that decreases sharply in the interface region to a closed-pack value within the bed. The streamwise velocity decreases near the fluid-particle interface and reaches Darcy velocity deep inside the bed. Drag force closure model based on the Ergun equation with correlations for permeability and Forchheimer tensor are evaluated using explicitly filtered, pore-resolved direct numerical simulation data at low Reynolds numbers. The closure model based on the Ergun equation works well deep inside the bed in the homogeneous porosity region, but overpredicts the drag in the fluid-particle interface region with inhomogeneous porosity variations. A uniform filter kernel width proportional to the particle size within the bed is shown to incorrectly sample large values from the free stream resulting in significantly higher drag in the transition region. A variable filter width bound by a unit Lipschitz constant that is proportional to the grid size in the freestream, rapidly increases in the interface region, and reaches a constant value proportional to the particle size inside the bed is devised to obtain a better representation of the velocity in the bed while avoiding non-physical oscillations in porosity. The variable filter width together with the assumption of an exponential Brinkman velocity solution in the interface region are used to develop a correction scheme that minimizes the error in the drag force compared to the filtered pore-resolved, direct numerical solution. The proposed correction and the model parameters are tested on a range of randomly packed bed porosities to show good predictive capability. |
Monday, November 25, 2024 3:21PM - 3:34PM |
R22.00008: Compressible Particle-Particle Interaction Implementation in Hydrocodes Smyther Hsiao, Frederick Ouellet, Jonathan D Regele Ejecta physics plays an important role in materials shocked by high explosives. When a shock impacts a rough surface of a solid material and melts it, the Richtmyer-Meshkov instability grows perturbations on the surface, which can eject particles. After release, the ejecta travel through the post-shock compressible flow. To simulate a large number of ejecta particles, an Euler-Lagrange approach is preferred, which requires modeling the subgrid-scale physics involved with fluid-particle interactions. We generalize the previous work from Hsiao et al. (Physical Review Fluids, 2023) to a system of moving particles subject to any loading shock in a fully functional hydro code. The following improvements were made: (1) The particles are allowed to move (2) Non-planar shocks are accounted for along with allowing for variable shock speeds. The generalized algorithm was tested with particle-resolved simulations for canonical test cases. The results of these tests are discussed and analyzed. |
Monday, November 25, 2024 3:34PM - 3:47PM |
R22.00009: A Multiphase Particle-In-Cell method for simulating particle dispersion in fluidized beds Federico Municchi, Keaton Brewster, Lei Funqiong, Gregory S Jackson Particle dispersion and mixing play a pivotal role in many applications in energy and chemical engineering. One example, are narrow-channel counter-flow fluidized bed heat exchangers, which offer a promising approach to transferring heat out of hot particles, because fluidization provides strong mixing and higher heat transfer coefficients. Such heat exchangers are core component in next-generation Concentrating Solar Power (CSP) plants, which employ high-temperature particle-based Thermal Energy Storage (TES). |
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