Preliminary experimental investigation on the interaction of a subaqueous dune like granular structure with a turbulent open channel flow
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| Format: | Preprint |
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2025
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| _version_ | 1866916761410994176 |
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| author | Roy, Durbar Ahmed, Ikbal Hakkim, Abdul Govindarajan, Rama |
| author_facet | Roy, Durbar Ahmed, Ikbal Hakkim, Abdul Govindarajan, Rama |
| contents | We study the interaction of a subaqueous dune like granular structure with a turbulent open channel flow experimentally using optical diagnostics in the Shields and Froude parameter space ($0.05{\leq}θ{\leq}0.32$, $0.1{\leq}Fr{\leq}0.4$). Interactions between the turbulent flow and the granular structure give rise to transient erosion-deposition dynamics leading to various types of particle transport. The subaqueous structures in the channel bed evolves due to shear-stress-induced erosion, gravity-driven deposition, and subsequent particle transport. We study the centroid motion and the granular structure shape evolution. At lower end of our $θ-Fr$ parameter space, we observe no erosion and the structure remains at rest. We show that the critical Shields number ($θ_{cr}$) is of the order of $0.1$ beyond which erosion starts to occur. At intermediate values of $θ$ and $Fr$ we observe slow erosion, resulting in a rigid body motion of the granular structure without significant shape deformation. Higher values of $θ$ and $Fr$ causes vortex formation at the upstream of the dune resulting in stronger erosion, rapid shape deformation and relatively higher translation velocity of the centroid. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_10111 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Preliminary experimental investigation on the interaction of a subaqueous dune like granular structure with a turbulent open channel flow Roy, Durbar Ahmed, Ikbal Hakkim, Abdul Govindarajan, Rama Soft Condensed Matter Fluid Dynamics We study the interaction of a subaqueous dune like granular structure with a turbulent open channel flow experimentally using optical diagnostics in the Shields and Froude parameter space ($0.05{\leq}θ{\leq}0.32$, $0.1{\leq}Fr{\leq}0.4$). Interactions between the turbulent flow and the granular structure give rise to transient erosion-deposition dynamics leading to various types of particle transport. The subaqueous structures in the channel bed evolves due to shear-stress-induced erosion, gravity-driven deposition, and subsequent particle transport. We study the centroid motion and the granular structure shape evolution. At lower end of our $θ-Fr$ parameter space, we observe no erosion and the structure remains at rest. We show that the critical Shields number ($θ_{cr}$) is of the order of $0.1$ beyond which erosion starts to occur. At intermediate values of $θ$ and $Fr$ we observe slow erosion, resulting in a rigid body motion of the granular structure without significant shape deformation. Higher values of $θ$ and $Fr$ causes vortex formation at the upstream of the dune resulting in stronger erosion, rapid shape deformation and relatively higher translation velocity of the centroid. |
| title | Preliminary experimental investigation on the interaction of a subaqueous dune like granular structure with a turbulent open channel flow |
| topic | Soft Condensed Matter Fluid Dynamics |
| url | https://arxiv.org/abs/2504.10111 |