Streak formation in flow over biomimetic fish scale arrays
| Autor: | Muthukumar Muthuramalingam, Christoph Bruecker, Leo S. Villemin |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
0106 biological sciences
Flow visualization Male Materials science Carps Physiology 030310 physiology Flow (psychology) Animal Scales Streak FOS: Physical sciences Geometry Aquatic Science Boundary layer thickness 010603 evolutionary biology 01 natural sciences Biophysical Phenomena Physics::Fluid Dynamics 03 medical and health sciences Biomimetics Water Movements Animals SF Molecular Biology Ecology Evolution Behavior and Systematics Swimming 0303 health sciences Fluid Dynamics (physics.flu-dyn) Scale height Laminar flow Physics - Fluid Dynamics Boundary layer Drag Insect Science Animal Science and Zoology Bass Female TJ |
| ISSN: | 0022-0949 |
| Popis: | The surface topology of the scale pattern from the European Sea Bass (Dicentrarchus labrax ) was measured using a digital microscope and geometrically reconstructed using Computer Assisted Design modelling. Numerical flow simulations and experiments with a physical model of the surface pattern in a flow channel mimic the flow over the fish surface with a laminar boundary layer. The scale array produces regular rows of alternating, streamwise low-speed and high-speed streaks inside the boundary layer close to the surface, with maximum velocity difference of about 9%. Low-velocity streaks are formed in the central region of the scales whereas the high-velocity streaks originated in the overlapping region between the scales. Thus, those flow patterns are linked to the arrangement and the size of the overlapping scales within the array. Because of the velocity streaks, total drag reduction is found when the scale height is small relative to the boundary layer thickness, i.e. less than 10%. Flow simulations results were compared with surface oil-flow visualisations on the physical model of the surface placed in a flow channel. The results show an excellent agreement in the size and arrangement of the streaky structures. From comparison to recent literature about micro-roughness effects on laminar boundary layer flows it is hypothesized that the fish scales could delay transition which would further reduce the drag. Comment: 14 pages, 9 figures |
| Databáze: | OpenAIRE |
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