Turbulent flows over porous lattices: alteration of near-wall turbulence and pore-flow amplitude modulation
| العنوان: | Turbulent flows over porous lattices: alteration of near-wall turbulence and pore-flow amplitude modulation |
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| المؤلفون: | Habibi Khorasani, Seyed Morteza, Luhar, Mitul, Bagheri, Shervin, 1979 |
| المصدر: | Journal of Fluid Mechanics. 984 |
| مصطلحات موضوعية: | Turbulence simulation, mixing enhancement, flow–structure interactions |
| الوصف: | Turbulent flows over porous lattices consisting of rectangular cuboid pores are investigated using scale-resolving direct numerical simulations. Beyond a certain threshold which is primarily determined by the wall-normal Darcy permeability, Ky, near-wall turbulence transitions from its canonical regime, marked by the presence of streak-like structures, to another marked by the presence of Kelvin-Helmholtz-like (K-H-like) spanwise-coherent structures. The threshold agrees well with that previously established in studies where permeable-wall boundary conditions had been used as surrogates for a porous substrate. In the smooth-wall-like regime, none of the investigated substrates demonstrate any reduction in drag relative to a smooth-wall flow. At the permeable surface, a notable component of the flow is that which adheres to the pore geometry and undergoes modulation by the turbulent scales of motions due to the interaction mechanism described by Abderrahaman-Elena et al. (2019). Its resulting effect can be quantified in terms of an amplitude modulation (AM) using the approach of Mathis et al. (2009). This pore-coherent flow component persists throughout the porous substrate, highlighting the importance of a given substrate's microstructure in the presence of an overlying turbulent flow. This geometry-related aspect of the flow is not accounted for when continuum-based models for a porous medium or effective representations of them such as wall boundary conditions are used. The intensity of the AM effect is enhanced in the K-H-like regime and becomes strengthened with larger permeability. As a result, structured porous materials may be designed to exploit or mitigate these flow features depending upon the intended application. |
| وصف الملف: | |
| URL الوصول: | https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-344648 https://doi.org/10.1017/jfm.2024.198 https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/turbulent-flows-over-porous-lattices-alteration-of-nearwall-turbulence-and-poreflow-amplitude-modulation/1360547B98112F46DE56F6EE047C9090 |
| قاعدة البيانات: | SwePub |
| تدمد: | 00221120 |
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| DOI: | 10.1017/jfm.2024.198 |