On the Rarefied Thermally-Driven Flows in Cavities and Bends
This study examined rarefied thermally-driven flow in a square cavity (Case 1) and rectangular bend (Case 2), with various uniform wall temperatures in two dimensions. We employed the direct simulation Monte Carlo (DSMC) to solve problems with a wide range of Knudsen numbers Kn = 0.01 to 10, and the...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-11-01
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| Series: | Fluids |
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| Online Access: | https://www.mdpi.com/2311-5521/7/11/354 |
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| author | Mostafa Mousivand Ehsan Roohi |
| author_facet | Mostafa Mousivand Ehsan Roohi |
| author_sort | Mostafa Mousivand |
| collection | DOAJ |
| description | This study examined rarefied thermally-driven flow in a square cavity (Case 1) and rectangular bend (Case 2), with various uniform wall temperatures in two dimensions. We employed the direct simulation Monte Carlo (DSMC) to solve problems with a wide range of Knudsen numbers Kn = 0.01 to 10, and the discrete unified gas kinetic scheme (DUGKS) solver was used at Kn = 0.01. The scenario was that, in case 1, the bottom side and its opposite were set hot, and the other sides were set cold. Diffuse reflector boundary conditions were set for all walls. The imposed temperature differences created four primary vortices. The results of the continuum set of equations of the slow non-isothermal flow (SNIT) solver proved that the primary vortices in the square cavity were caused by nonlinear thermal stress effects, and other smaller vortices appearing at Kn = 0.01, 0.1 were brought about by thermal creep processes. As the Kn increased, vortices generated by thermal creep disappeared, and eddies created by nonlinear thermal stress occupied the cavity. In case 2, i.e., a rectangular bend, two sides were set cold, and the others were hot. Two primary vortices were formed, which were caused by nonlinear thermal stress effects. The direction of streamlines in the two main vortices was opposite, from the warm to the cold zone, as some eddies on the left were counterclockwise, and others were clockwise. |
| first_indexed | 2024-03-09T18:20:15Z |
| format | Article |
| id | doaj.art-14390c3d8e484b84ba955d69c97df31a |
| institution | Directory Open Access Journal |
| issn | 2311-5521 |
| language | English |
| last_indexed | 2024-03-09T18:20:15Z |
| publishDate | 2022-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Fluids |
| spelling | doaj.art-14390c3d8e484b84ba955d69c97df31a2023-11-24T08:20:18ZengMDPI AGFluids2311-55212022-11-0171135410.3390/fluids7110354On the Rarefied Thermally-Driven Flows in Cavities and BendsMostafa Mousivand0Ehsan Roohi1High Performance Computing (HPC) Laboratory, Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, IranHigh Performance Computing (HPC) Laboratory, Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, IranThis study examined rarefied thermally-driven flow in a square cavity (Case 1) and rectangular bend (Case 2), with various uniform wall temperatures in two dimensions. We employed the direct simulation Monte Carlo (DSMC) to solve problems with a wide range of Knudsen numbers Kn = 0.01 to 10, and the discrete unified gas kinetic scheme (DUGKS) solver was used at Kn = 0.01. The scenario was that, in case 1, the bottom side and its opposite were set hot, and the other sides were set cold. Diffuse reflector boundary conditions were set for all walls. The imposed temperature differences created four primary vortices. The results of the continuum set of equations of the slow non-isothermal flow (SNIT) solver proved that the primary vortices in the square cavity were caused by nonlinear thermal stress effects, and other smaller vortices appearing at Kn = 0.01, 0.1 were brought about by thermal creep processes. As the Kn increased, vortices generated by thermal creep disappeared, and eddies created by nonlinear thermal stress occupied the cavity. In case 2, i.e., a rectangular bend, two sides were set cold, and the others were hot. Two primary vortices were formed, which were caused by nonlinear thermal stress effects. The direction of streamlines in the two main vortices was opposite, from the warm to the cold zone, as some eddies on the left were counterclockwise, and others were clockwise.https://www.mdpi.com/2311-5521/7/11/354rarefied flowsquare cavitydirect simulation Monte Carlo (DSMC)nonlinear thermal stressthermal creep |
| spellingShingle | Mostafa Mousivand Ehsan Roohi On the Rarefied Thermally-Driven Flows in Cavities and Bends Fluids rarefied flow square cavity direct simulation Monte Carlo (DSMC) nonlinear thermal stress thermal creep |
| title | On the Rarefied Thermally-Driven Flows in Cavities and Bends |
| title_full | On the Rarefied Thermally-Driven Flows in Cavities and Bends |
| title_fullStr | On the Rarefied Thermally-Driven Flows in Cavities and Bends |
| title_full_unstemmed | On the Rarefied Thermally-Driven Flows in Cavities and Bends |
| title_short | On the Rarefied Thermally-Driven Flows in Cavities and Bends |
| title_sort | on the rarefied thermally driven flows in cavities and bends |
| topic | rarefied flow square cavity direct simulation Monte Carlo (DSMC) nonlinear thermal stress thermal creep |
| url | https://www.mdpi.com/2311-5521/7/11/354 |
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