Journal article
Flow and Entrainment Mechanisms Around a Freshwater Mussel Aligned With the Incoming Flow
Water resources research, Vol.56(9), e2020WR027983
09/2020
DOI: 10.1029/2020WR027983
Abstract
The paper uses information from eddy‐resolving simulations to characterize flow and turbulence around freshwater mussels at the organism scale. The focus is on the simplest case of a partially burrowed, isolated mussel aligned with the incoming flow in an open channel. The wake structure and the capacity of the flow to displace the mussel from the bed substrate and to induce local scour around the mussel are investigated as a function of the ratio between the height of the exposed part of the mussel, h, and the total mussel height, d, and as a function of the filtration velocity ratio (VR) between the incoming channel flow velocity, U0, and the mean velocity inside the excurrent siphon, Ue. As opposed to the flow past most surface‐mounted obstacles where the bed shear stresses are reduced in the wake of the body, the capacity of the flow to induce bed erosion behind isolated mussels aligned with the flow is relatively large because of strong downwelling motions inside the horizontal separated shear layers. These flow features are associated with the formation of counterrotating base vortices of unequal coherence that induce upwash behind the mussel. The total circulation of the base vortices increases with increasing h/d and VR. Though both symmetrical and antisymmetrical shedding are observed in the wake, the antisymmetrical mode dominates, and its strength increases with increasing VR. The nondimensional streamwise force acting on the emerged part of the mussel's shell increases with increasing h/d and VR. Finally, the paper discusses the effects of varying h/d and VR on the dynamics and dilution of the jet of filtered water originating in the excurrent siphon, which is important to understand how mussels affect mixing and water quality (e.g., nutrient availability and phytoplankton concentration) in natural streams.
Key Points
Wake region behind an isolated mussel is a region of high bed shear stress
Counterrotating base vortices form in the wake of the partially burrowed mussel; they induce strong upwelling and downwelling motions in the wake
Though the symmetric shedding mode is present, the antisymmetric shedding mode dominates in the wake of partially burrowed mussels
Details
- Title: Subtitle
- Flow and Entrainment Mechanisms Around a Freshwater Mussel Aligned With the Incoming Flow
- Creators
- Hao Wu - The University of IowaGeorge Constantinescu - The University of IowaJie Zeng - South Florida Water Management District
- Resource Type
- Journal article
- Publication Details
- Water resources research, Vol.56(9), e2020WR027983
- DOI
- 10.1029/2020WR027983
- ISSN
- 0043-1397
- eISSN
- 1944-7973
- Number of pages
- 24
- Grant note
- EAR Hydrologic Sciences Program of the U.S. National Science Foundation (1659518)
- Language
- English
- Date published
- 09/2020
- Academic Unit
- Civil and Environmental Engineering; IIHR--Hydroscience and Engineering
- Record Identifier
- 9984066104202771
Metrics
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