Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study
Particles are present in many natural and industrial multiphase flows. In most practical cases, particle shape is not spherical, leading to additional difficulties for numerical studies. In this paper, DNS of turbulent channel flows with finite-size prolate spheroids is performed. The geometry inclu...
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| Format: | Article |
| Language: | English |
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AIP Publishing LLC
2017-09-01
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| Series: | AIP Advances |
| Online Access: | http://dx.doi.org/10.1063/1.5002528 |
| _version_ | 1830479004905242624 |
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| author | Amir Eshghinejadfard Seyed Ali Hosseini Dominique Thévenin |
| author_facet | Amir Eshghinejadfard Seyed Ali Hosseini Dominique Thévenin |
| author_sort | Amir Eshghinejadfard |
| collection | DOAJ |
| description | Particles are present in many natural and industrial multiphase flows. In most practical cases, particle shape is not spherical, leading to additional difficulties for numerical studies. In this paper, DNS of turbulent channel flows with finite-size prolate spheroids is performed. The geometry includes a straight wall-bounded channel at a frictional Reynolds number of 180 seeded with particles. Three different particle shapes are considered, either spheroidal (aspect ratio λ=2 or 4) or spherical (λ=1). Solid-phase volume fraction has been varied between 0.75% and 1.5%. Lattice Boltzmann method (LBM) is used to model the fluid flow. The influence of the particles on the flow field is simulated by immersed boundary method (IBM). In this Eulerian-Lagrangian framework, the trajectory of each particle is computed individually. All particle-particle and particle-fluid interactions are considered (four-way coupling). Results show that, in the range of examined volume fractions, mean fluid velocity is reduced by addition of particles. However, velocity reduction by spheroids is much lower than that by spheres; 2% and 1.6%, compared to 4.6%. Maximum streamwise velocity fluctuations are reduced by addition of particle. By comparing particle and fluid velocities, it is seen that spheroids move faster than the fluid before reaching the same speed in the channel center. Spheres, on the other hand, move slower than the fluid in the buffer layer. Close to the wall, all particle types move faster than the fluid. Moreover, prolate spheroids show a preferential orientation in the streamwise direction, which is stronger close to the wall. Far from the wall, the orientation of spheroidal particles tends to isotropy. |
| first_indexed | 2024-12-21T16:39:37Z |
| format | Article |
| id | doaj.art-08630a643a5e4c97846f7bc32b4091cd |
| institution | Directory Open Access Journal |
| issn | 2158-3226 |
| language | English |
| last_indexed | 2024-12-21T16:39:37Z |
| publishDate | 2017-09-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | AIP Advances |
| spelling | doaj.art-08630a643a5e4c97846f7bc32b4091cd2022-12-21T18:57:08ZengAIP Publishing LLCAIP Advances2158-32262017-09-0179095007095007-1810.1063/1.5002528027709ADVFully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann studyAmir Eshghinejadfard0Seyed Ali Hosseini1Dominique Thévenin2Laboratory of Fluid Dynamics and Technical Flows, University of Magdeburg “Otto von Guericke”, Universitätsplatz 2, 39106 Magdeburg, GermanyLaboratory of Fluid Dynamics and Technical Flows, University of Magdeburg “Otto von Guericke”, Universitätsplatz 2, 39106 Magdeburg, GermanyLaboratory of Fluid Dynamics and Technical Flows, University of Magdeburg “Otto von Guericke”, Universitätsplatz 2, 39106 Magdeburg, GermanyParticles are present in many natural and industrial multiphase flows. In most practical cases, particle shape is not spherical, leading to additional difficulties for numerical studies. In this paper, DNS of turbulent channel flows with finite-size prolate spheroids is performed. The geometry includes a straight wall-bounded channel at a frictional Reynolds number of 180 seeded with particles. Three different particle shapes are considered, either spheroidal (aspect ratio λ=2 or 4) or spherical (λ=1). Solid-phase volume fraction has been varied between 0.75% and 1.5%. Lattice Boltzmann method (LBM) is used to model the fluid flow. The influence of the particles on the flow field is simulated by immersed boundary method (IBM). In this Eulerian-Lagrangian framework, the trajectory of each particle is computed individually. All particle-particle and particle-fluid interactions are considered (four-way coupling). Results show that, in the range of examined volume fractions, mean fluid velocity is reduced by addition of particles. However, velocity reduction by spheroids is much lower than that by spheres; 2% and 1.6%, compared to 4.6%. Maximum streamwise velocity fluctuations are reduced by addition of particle. By comparing particle and fluid velocities, it is seen that spheroids move faster than the fluid before reaching the same speed in the channel center. Spheres, on the other hand, move slower than the fluid in the buffer layer. Close to the wall, all particle types move faster than the fluid. Moreover, prolate spheroids show a preferential orientation in the streamwise direction, which is stronger close to the wall. Far from the wall, the orientation of spheroidal particles tends to isotropy.http://dx.doi.org/10.1063/1.5002528 |
| spellingShingle | Amir Eshghinejadfard Seyed Ali Hosseini Dominique Thévenin Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study AIP Advances |
| title | Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study |
| title_full | Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study |
| title_fullStr | Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study |
| title_full_unstemmed | Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study |
| title_short | Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study |
| title_sort | fully resolved prolate spheroids in turbulent channel flows a lattice boltzmann study |
| url | http://dx.doi.org/10.1063/1.5002528 |
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