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 U36: Particle-Laden Flows: Modeling, Theory, and Experimentation I |
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Chair: Shankar Subramaniam, Iowa State University Room: 244 |
Tuesday, November 22, 2022 8:00AM - 8:13AM |
U36.00001: PIV and CFD-DEM simulation of gas jet fluidization of a 1mm ceramic particle bed William D Fullmer, Ann S Almgren, Ray Cocco, Jonathan E Higham, Christine M Hrenya, Casey Q LaMarche, Jordan Musser, Andrew Myers, Roberto Porcu, Deepak Rangarajan, Justin Weber Experiments were conducted at PSRI in 2016 studying high-speed horizontal gas jets penetrating into a marginally fluidized bed of semicircular cross-section. Previous efforts have focused on the largest particles of the dataset, 6mm and 3mm diameter, which are more appealing as numerical validation data due to manageable particle counts. In this work, we focus on ceramic beads 1mm in diameter. The experimental data from this material had not yet been fully characterized because the bed contains approximately 7 million particles, making parametric study with a discrete particle model computationally expensive. However, the recent development of MFIX-Exa, a massively parallel, AMReX-enabled CFD-DEM code, as made such simulations much more reasonable. We present the results of the PIV analysis of the velocity field and compare to simulations adjusting the drag calibration method, the jet resolution method, and the fluid continuity approximation. |
Tuesday, November 22, 2022 8:13AM - 8:26AM |
U36.00002: Interaction of inertial particles falling in a quiescent, density-stratified, two-layer medium Soohyeon Kang, Liu Hong, Shyuan Cheng, Susan Kieffer, Jim Best, Leonardo Chamorro Motivated by observations and modelds of the May 18, 1980, eruption of Mount St. Helens, WA, we studied the interaction, pair dispersion, and Lagrangian features of spherical particles falling in a two-liquid, quiescent medium composed of combinations of oil, ethanol, and water-glycerin mixtures. Spherical glass particles of diameters 1, 2, 4 mm were released continuosly at constant rate using a customized system that kept the inital particle separation consistant. Particle trajectories and velocities were quantified using a particle tracking velocimetry system composed of two high-speed cameras mounted perpendicularly. On the order of a thousand particles were tracked for each scenario. We explored the role of Galileo number, particle/fluid density ratio, the buoyancy jump between two fluid layers, and the initial separation of the falling particles upon their settling behavior. The results show the significant modulation generated by fluid stratification and the density interface on the dispersion and Lagransian features of the falling particles. |
Tuesday, November 22, 2022 8:26AM - 8:39AM |
U36.00003: Critical examination on particle leakage through the exhalation valve on a face mask Yeeun Kang, Jooyeon Park, Hyungmin Park We experimentally evaluate the particle penetration through the exhalation valve induced by the airflow simulating the human respiration. The bi-directional jet flow in the range of 20 - 80 L/min is applied on the two representative valve types (square and circular) in three different conditions: exhalation, inhalation, and periodic flows. To mimic hazardous airborne particulate matters, we used Silicon particles (6 um in size). For each case, the airflow is measured by adaptive PIV, and the particle distribution is obtained using planar nephelometry. During the exhalation, the high-speed jet is generated through the flap opening, inducing entrainment of surrounding air and trapping particles inside the recirculation region under the jet. In the inhalation, reasonable protection from external pollutants is achieved except for the circular valve in lower flowrate. For the periodic flow, particle penetrates instant the flap closes in the square valve owing to the discrepancy in the response time of the particles and the flap to the airflow and for the circular valve, particle penetrates steadily over time due to the imperfect sealing. |
Tuesday, November 22, 2022 8:39AM - 8:52AM |
U36.00004: Vortex merger in semi-dilute particle-laden flow shuai shuai, Mohamed H KASBAOUI, Anubhab Roy, Darish J Dhas We investigate the effect of inertial particles on the merger of a pair of co-rotating vortices in semi-dilute particle-laden flows. Unlike the merger process in particle-free flows where the separation between two vortex centers decreases monotonically, we show that the feedback force exerted by the suspended particles on the carrier fluid modulates the merger mechanism and may even inhibit it depending on the particle inertia. We perform a series of Eulerian-Lagrangian simulations at the circulation Reynolds number 500 and mass loading M=1. Particle diameter is varied such that the resulting Stokes number, which measures inertia, varies from 0.01 to 0.8. For particles with low inertia (St<0.05), the merger is delayed due to the suspension acting as an effective fluid with density (1+M) higher than that of the carrier fluid. For particles with moderate inertia (0.05 |
Tuesday, November 22, 2022 8:52AM - 9:05AM |
U36.00005: Point-cloud Subgrid Particle-Averaged Reynolds Stress Equivalent (SPARSE) method for particle-laden flows with stochastic forcing Daniel Domínguez Vázquez, Gustaaf B Jacobs For process scale problems in particle-laden flows described with Eulerian-Lagrangian (EL) formulations where the Particle-Source-In-Cell (PSIC) method is used, it is often needed to compute millions to billions of particles where a reduced modeling is needed. The point-particle assumption considers particles as single points and models the momentum and energy exchanged between phases because their analytical descriptions are only available in scarce physical situations. The forcing of the particle phase is thus corrected with empirical and/or data-driven correlations that introduce uncertainty, rendering the particle equations stochastic. The double purpose of alleviating the computational cost and including the stochastic character of the forcing is addressed here using the Subgrid Particle-Averaged Reynolds Stress Equivalent (SPARSE) method. The point-cloud SPARSE method averages the dispersed phase in Lagrangian form, leading to a closed set of equations to describe the first two moments of stochastically forced particle clouds. The resulting formulation is scalable to three-dimensional complex flows. We test the SPARSE formulation in elementary analytical flows and with an isotropic turbulence case computed with a DNS solver. |
Tuesday, November 22, 2022 9:05AM - 9:18AM |
U36.00006: A spatially-correlated random walk model for capturing two-point statistics in turbulent particle-laden flows Max P Herzog, John Wakefield, Shankar Subramaniam, Jesse Capecelatro We present a modeling framework designed to capture two-point statistics of inertial particles in turbulent flows. Stochastic models are widely used in large-eddy simulations (LES) and Reynolds-averaged Navier-Stokes (RANS) simulations due to their ability in predicting one-point fluid statistics (e.g., velocity variance and autocorrelation) and their insensitivity to grid coarsening. Modeling the subgrid-scale velocity field as an independent stochastic process, however, prevents such models from capturing spatial heterogeneity (e.g., preferential concentration and particle pair dispersion). In this work, a spatially correlated random walk (SCRW) model is proposed based on an Ornstein-Uhlenbeck (OU) process with a spatially varying covariance matrix that embeds two-point particle information. The covariance matrix is quantified from direct numerical simulations of inertial particles in homogeneous isotropic turbulence. Computational and analytical challenges associated with the high dimensionality of the model are addressed and a path forward is presented. |
Tuesday, November 22, 2022 9:18AM - 9:31AM |
U36.00007: Drifting and twirling in a chiral active fluid at low Reynolds number Tali Khain, Colin R Scheibner, Michel Fruchart, Tom Witten, Vincenzo Vitelli Chiral fluids - such as fluids under rotation or a magnetic field as well as synthetic and biological active fluids - flow in a different way than ordinary ones. Here, we ask: how does the flow bend around a moving obstacle in the fluid? In chiral fluids, the viscosity tensor acquires additional coefficients that are parity-violating (not invariant under mirror reflections of space) and non-dissipative (odd). This modifies the velocity field in the incompressible Stokes regime in three dimensions. For instance, a sedimenting sphere generates rotational motion in the flow. Nonetheless, due to the symmetry of the flow, the torque on the sphere is zero, so it does not rotate. More generally, in the low Reynolds number regime, the response of a rigid body to forces and torques is given by the mobility matrix, which depends on the viscous properties of the fluid and the geometry of the body. By analyzing the symmetries of the mobility matrix, we constrain the possible motions of a general rigid body immersed in a parity-violating fluid. To further explore the trajectories of differently shaped particles, we model each object with a collection of Stokeslets, which allows for a numerical approximation of the mobility matrix. Applied to the context of sedimentation, our work shows that non-chiral particles can begin to spin as they sink under gravity. |
Tuesday, November 22, 2022 9:31AM - 9:44AM |
U36.00008: Chaotic Behaviour of Multiple Immersed Ellipsoids Andrew Boyd, Prashant Valluri, Erich Essmann, Rama Govindarajan, David Scott, Mark Sawyer
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Tuesday, November 22, 2022 9:44AM - 9:57AM |
U36.00009: Contaminant Transport in New York City using the coupled EL method and finite-time Lyapunov exponents Wayne R Oaks, Ali Khosronejad The release of contaminants in heavily populated urban locations such as New York City has become a major concern for public safety. This research addresses the transport of contaminant particles from a point source in a 2.5 km long and highly-populated area of Lower Manhattan starting just south of Battery Park. A computational grid system with approximately 76 million grid points is used to resolve the flow while the immersed boundary method is employed to resolve the geometry of the buildings, roads, and other objects including many skyscrapers of varying heights. A large eddy simulation was used to resolve the wind flow within the study area. The contaminate was modeled as particles and traced using the coupled Eulerian-Lagrangian method. We found that the windward contaminant propagation velocity was 52% of the prevailing wind velocity of 3.6 m/s. Once the pollutant source is removed, the pollutant particles propagate out of the study area at 16% of the prevailing wind velocity. |
Tuesday, November 22, 2022 9:57AM - 10:10AM |
U36.00010: Detailed measurements on particle-turbulence interaction within the suspension layer of a symmetric oscillatory sheet flow Chang Liu, Kenneth T Kiger The particle-resolved coupled dynamics between sediment particles and turbulence under sheet flow conditions remains an open problem due to the prohibitive computational expense in direct simulation and harsh imaging environment in experimental measurements. Enabled by the recently developed apertured filter method, a whole field, phase-locked time-resolved, particle-resolved and concurrent measurement of both the fluid and the sediment phase was conducted within the suspension layer up to a concentration of C = 1% in a symmetric oscillatory sheet flow (period T = 5s, free stream velocity Uo = 1m/s, sediment mean diameter d = 240μm). At every 10○, the instantaneous sediment particle 3D locations within a well-defined measurement volume (around 1mm thick) were reconstructed and their temporal trajectories were computed; on the same measurement plane, carrier phase flow velocities (2D3C) were calculated by stereoscopic particle image velocimetry with a resolution of 1.6mm. Analysis will be focused upon the coupled dynamics between phases manifested at different phase angles. The evolution of slip velocity profiles, preferential concentrations, and modulated turbulent statistics are presented, providing explanations for the resultant sediment concentration profiles. |
Tuesday, November 22, 2022 10:10AM - 10:23AM |
U36.00011: Entrainment by a plume of microscopic particles falling in air Alec J Petersen, Filippo Coletti While multiphase plumes are widespread in natural and industrial settings, particle plumes remain scarcely studied and poorly understood, in particular in gas-solid systems. Their dynamics is instead crucial to environmental issues associated to, for example, mining operations and volcanic eruptions. We perform experiments on 30-micrometer glass spheres falling at high concentrations into otherwise quiescent air. Using high-speed particle image velocimetry and particle tracking velocimetry, we characterize the plume velocity and spreading rate, highlighting fundamental differences with single-phase plumes. Moreover, using multiple camera views, we track the plume interface and measure the surrounding air motion to calculate the entrainment rate. The latter informs a one-dimensional model based on mass and momentum conservation of both phases, which compares favorably with the experimental observation. The measurements reveal that, over the considered range of parameters and unlike single-phase shear flows, entrainment is largely driven by engulfment over large billows formed by an interface that does not exhibit fractal properties. |
Tuesday, November 22, 2022 10:23AM - 10:36AM |
U36.00012: Fluid structure interaction simulation of subaqueous spherical objects: Soft sphere collision Dominik Worf, Ali Khosronejad, Christine Sindelar Sustainable sediment transport management is one of the big challenges in river engineering regarding hydraulic structures and environmental conservation. The mechanics of sediment transport still require a lot of research. In bedload sediment transport, the motion of about 30% of moving particles is initiated by near field interactions and collisions. Thus, collision models for these types of interactions among the sediment particles are required. |
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