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particle resolved direct numerical simulation of heat transfer in gas-solid flows

INTERNATIONAL JOURNAL OF COMPUTING SCIENCE AND MATHEMATICS 2023年第2期18卷 103-112页

作者： Zaidi, Ali Abbas Univ Manitoba Dept Mech Engn 75A Chancellors Circle Winnipeg MB R3T 5V6 Canada

The purpose of this paper is to propose a new immersed boundary method for heat transfer calculations in gas-solid flows. In the proposed method, solid particles are fixed in the computational domain due to longer response times of particles (to mimic the gas-solid systems) and treated as sources of velocity and temperature. For calculations of fluid velocity and temperature, Navier-Stokes and energy equations are solved for fixed Cartesian grid. For the validation of the proposed method, number of benchmarking studies are done by comparing the simulation results with the studied problems in literature. simulations showed good agreement with the literature results which verifies the accuracy and reliability of the immersed boundary method proposed in this paper.

关键词： immersed boundary method particle resolved direct numerical simulation porous medium heat transfer computational fluid dynamics

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Towards accelerating particle-resolved direct numerical simulation with neural operators

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STATISTICAL ANALYSIS AND DATA MINING 2024年第3期17卷

作者： Atif, Mohammad Lopez-Marrero, Vanessa Zhang, Tao Sharfuddin, Abdullah Al Muti Yu, Kwangmin Yang, Jiaqi Yang, Fan Ladeinde, Foluso Liu, Yangang Lin, Meifeng Li, Lingda Brookhaven Natl Lab Computat Sci Initiat Upton NY 11973 USA SUNY Stony Brook IACS Stony Brook NY USA Brookhaven Natl Lab Environm & Climate Sci Dept Upton NY USA SUNY Stony Brook Dept Mech Engn Stony Brook NY USA Emory Univ Dept Math Atlanta GA USA

We present our ongoing work aimed at accelerating a particle-resolved direct numerical simulation model designed to study aerosol-cloud-turbulence interactions. The dynamical model consists of two main components-a set of fluid dynamics equations for air velocity, temperature, and humidity, coupled with a set of equations for particle (i.e., cloud droplet) tracing. Rather than attempting to replace the original numerical solution method in its entirety with a machine learning (ML) method, we consider developing a hybrid approach. We exploit the potential of neural operator learning to yield fast and accurate surrogate models and, in this study, develop such surrogates for the velocity and vorticity fields. We discuss results from numerical experiments designed to assess the performance of ML architectures under consideration as well as their suitability for capturing the behavior of relevant dynamical systems.

关键词： fluid dynamics machine learning neural operators particle resolved direct numerical simulation

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An Accurate and Scalable direction-Splitting Solver for Flows Laden with Non-Spherical Rigid Bodies–Part 1:Fixed Rigid Bodies

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Communications in Computational Physics 2023年第9期34卷 1079-1132页

作者： Aashish Goyal Anthony Wachs Department of Chemical and Biological Engineering University of British Columbia2360 East MallV6T 1Z3VancouverBritish ColumbiaCanada Department of Mathematics University of British Columbia1984 Mathematics RoadV6T 1Z4VancouverBritish ColumbiaCanada

particle-resolved direct numerical flow solvers predominantly use a projection method to decouple the non-linear mass and momentum conservation *** computing performance of such solvers often decays beyond O(1000)cores due to the cost of solving at least one large three-dimensional pressure Poisson problem per time *** parallelization may perform moderately well only or even poorly sometimes despite using an efficient algebraic multigrid preconditioner[38].We present an accurate and scalable solver using a direction splitting algorithm[12]to transform all three-dimensional parabolic/elliptic problems(and in particular the elliptic pressure Poisson problem)into a sequence of three one-dimensional parabolic sub-problems,thus improving its scalability up to multiple thousands of *** employ this algorithm to solve mass and momentum conservation equations in flows laden with fixed non-spherical rigid *** consider the presence of rigid bodies on the(uniform or non-uniform)fixed Cartesian fluid grid by modifying the diffusion and divergence stencils on the impacted grid node near the rigid body *** to[12],we use a higher-order interpolation scheme for the velocity field to maintain a secondorder stress estimation on the particle boundary,resulting in more accurate dimensionless coefficients such as drag C_(d)and lift C_(l).We also correct the interpolation scheme due to the presence of any nearby particle to maintain an acceptable accuracy,making the solver robust even when particles are densely packed in a sub-region of the computational *** present classical validation tests involving a single or multiple(up to O(1000))rigid bodies and assess the robustness,accuracy and computing speed of the *** further show that the direction Splitting solver is∼5 times faster on 5120 cores than our solver[38]based on a classical projection method[5].

关键词： Highly scalable solver particle-laden flow particle resolved direct numerical simulation incompressible flow non-spherical rigid bodies

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Study of flow resistance coefficients acting on regular non-spherical particles in simple shear flow at moderate Reynolds numbers

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POWDER TECHNOLOGY 2024年 435卷

作者： Lain, S. Castang, C. Sommerfeld, M. Univ Autonoma Occidente Mech Engn Dept PAI Grp Cali Colombia Otto Von Guericke Univ Fac Proc & Syst Engn Multiphase Flow Syst D-06120 Halle Saale Germany

This contribution is devoted to the study of the aerodynamic characteristics of non -spherical particles of definite regular shape, such as prolate and oblate ellipsoids as well as cylinders, immersed in a locally linear shear flow. The flow resistance coefficients of drag, lift and pitching torque are computed by means of the particle resolved direct numerical simulation (PR -DNS) technique for such shapes as function of the Reynolds number Re. The parameter space comprises particle aspect ratio, AR, fluid spin ratio, zeta, and particle orientation angle, alpha. The Reynolds numbers of interest are in the intermediate range 1 <= Re <= 100, common in industrial and environmental processes. To properly understand and explain the obtained results, the role of the friction and pressure contributions to total flow coefficients is analyzed in detail for the different cases, allowing the differences between the considered shapes to be pointed out. On the other hand, the behavior of the pressure and skin friction coefficients in the particle plane of symmetry parallel to the flow is investigated as a function of the previous parameters (shape, AR, zeta, alpha), which provides further insights into the features of the shear flow around the nonspherical particles at finite Re. Finally, the influence of the shear flow magnitude and incidence angle on the location of the center of aerodynamic force is devised for the three shapes considered as function of Reynolds number and particle aspect ratio. It is expected that the information generated in this work will be useful for researchers to enhance the modeling of non -spherical particles immersed in non -uniform flows.

关键词： particle resolved direct numerical simulation Non -spherical particles Regular shape Flow resistance coefficients

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A machine learning-based interaction force model for non-spherical and irregular particles in low Reynolds number incompressible flows

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POWDER TECHNOLOGY 2021年 392卷 632-638页

作者： Hwang, Soohwan Pan, Jianhua Fan, Liang-Shih Ohio State Univ William G Lowrie Dept Chem & Biomol Engn Columbus OH 43210 USA

In this study, interaction force of non-spherical particles in low Reynolds number gas-solid flow is investigated by neural network approaches. An artificial neural network (ANN) model is developed to correlate the non spherical particle shape and the flow conditions with the interaction force. To define the particle shape, spherical harmonic expansion is applied. Furthermore, variational autoencoder model is then used to extract latent geometric features. The latent vector is utilized as an input with the Reynolds number for the ANN. The interaction force data, which is used as output data of the ANN, is obtained by particle resolved direct numerical simulation for 5200 non-spherical particles. The proposed model enables unsupervised extraction for non-spherical particle shapes and accurate predictions on the interaction force without heavy computation. This study provides the model that can explain complicated shapes of particles and be applied to a large scale, computational fluid dynamics simulation. (c) 2021 Elsevier B.V. All rights reserved.

关键词： Non-spherical particle Artificial neural network Interaction force Spherical harmonic method Variational autoencoder particle resolved direct numerical simulation

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Residual Term of the Volume-Filtered Multiphase Flow Momentum Equation

Residual Term of the Volume-Filtered Multiphase Flow Momentu...

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作者： Ni, Menglin Iowa State University

学位级别：M.S., Master of Science/Master of Surgery

Spatial filtering of multiphase flow equations results in the volume-filtered Euler-Lagrange (VFEL) method that can efficiently simulate large domains, and capture a wide range of scales including mesoscale structures corresponding to particle clustering. However, spatial filtering results in unclosed residual terms in the VFEL equations which need to be modeled. These have been modeled using ensemble-averaged models, such as the average drag on a particle in a suspension (Capecelatro(2013)) for the residual filtered interphase momentum exchange term. Here we quantify the unclosed terms in the filtered momentum equation for a particle-laden suspension using particle resolved direct numerical simulation (PR-DNS). Using the indicator function approach we derive the exact interphase momentum exchange term, which differs slightly from the approximate expression given by Capecelatro (2013) for the interphase momentum exchange term that was based on simplifying assumptions of Anderson (1967). PR-DNS data from steady flow past a statistically homogenous particle assembly is filtered to quantify both exact and approximate versions of the interphase momentum exchange term for different filter widths. Analysis of the differences is used to provide insight into the range of validity of the existing deterministic model, and to provide direction for future scale-dependent stochastic models.

关键词： Multiphase flow particle resolved direct numerical simulation Volume-filtered Euler-Lagrange

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Aerodynamic coefficients of irregular non-spherical particles at intermediate Reynolds numbers

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POWDER TECHNOLOGY 2022年 402卷

作者： Castang, C. Lain, S. Garcia, D. Sommerfeld, M. Univ Autonoma Occidente Dept Energet & Mech PAI Grp Cali Colombia Otto Von Guericke Univ Fac Proc & Syst Engn Multiphase Flow Syst D-06120 Halle Saale Germany

In industrial processes such as those related with paper industry, coal or biomass combustion, particles can take irregular non-spherical shapes. However, in related numerical computations the assumption of spherical particle is customary, mainly because the fluid dynamic forces acting on such irregular particles are unknown to a large extent. This contribution aims to generate new information about the flow resistance coefficients (forces and torques) experienced by non-spherical irregular-shaped particles with three different degrees of sphericity psi (0.7, 0.8 and 0.89) immersed in a uniform flow at intermediate Reynolds numbers (i.e. Re = 1-200). For this pur-pose, particle resolved direct numerical simulations (PR-DNS) are carried out by means of the Ansys-Fluentcode using body fitted meshes where the irregular particle is well resolved. The flow coefficients are computed for a set of different particles belonging to the same sphericity group, considering a large number of orientations, which allows the construction of the corresponding distribution functions. Such distributions depend on Reynolds num-ber and particle sphericity and can be reasonably well approximated by Gaussian distributions, which are deter-mined by a mean value and a standard deviation. The obtained drag, lift and torque coefficients display expectedly a scattering around the mean values with a high sensitivity to the irregularity of the surface and par-ticle intrinsic aspect ratio (phi). Additionally, the distribution of the angle formed between the transverse lift force and the transverse torque in the plane orthogonal to the flow direction is computed. The generated information will be used to further pursue a novel statistical model for the fluid dynamic forces and torques acting on irregular particles in the frame of the Lagrangian approach.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// ***/licenses

关键词： particle resolved direct numerical simulation Non-spherical particles Irregular shape Sphericity Flow resistance coefficients

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