Study on the Drag Reduction Characteristics of the Surface Morphology of Paramisgurnus dabryanus Loach

Abstract

The drag reduction design of underwater vehicles is of great significance to saving energy and enhancing speed. In this paper, the drag reduction characteristics of Paramisgurnusdabryanus loach was explored using 3D ultra-depth field microscopy to observe the arrangement of the scales. Then, a geometric model was established and parameterized. A simulated sample was processed by computer numerical control (CNC) machining and tested through using a flow channel bench. The pressure drop data were collected by sensors, and the drag reduction rate was consequently calculated. The test results showed that the drag reduction rate of a single sample could reach 23% at a speed of 1.683 m/s. Finally, the experimental results were verified by numerical simulation and the drag reduction mechanism was explored. The boundary layer theory and RNG k-ε turbulence model were adopted to analyze the velocity contour, pressure contour and shear force contour diagrams. The numerical simulation results showed that a drag reduction effect could be achieved by simulating the microstructure of scales of the Paramisgurnusdabryanus loach, showing that the results are consistent with the flow channel experiment and can reveal the drag reduction mechanism. The bionic surface can increase the thickness of boundary layer, reduce the Reynolds number and wall resistance. The scales disposition of Paramisgurnusdabryanus loach can effectively reduce the surface friction, providing a reference for future research on drag reduction of underwater vehicles such as ships and submarines.

A Bio-Inspired Drag Reduction Method of Bionic Fish Skin Mucus Structure

“…The circulating water medium was maintained at 20 °C, and it entered the pressure detection device through a water pump, with water velocity controlled by a flow regulator. Within the pressure detection device, two sensors were employed to collect pressure values at both ends of the sample [ 20 ]. The flow rate of mucous within the sample was controlled using a mucous injection device.…”

“…The drag reduction rate of the mucous release surface compared to the smooth surface could be calculated using Equation (1). In the simulation results, the total resistance (F) was composed of pressure difference resistance (F dp ) and viscous resistance (F v ) [20]. The main factors affecting pressure difference resistance include cross-sectional area, object shape, and the orientation in the flow field.…”

Multiscale Wear Simulation in Textured, Lubricated Contacts

“…Patir and Cheng [30,31] considered this influence with factors in the Reynolds equation. For the observed case of the lubrication gap, pressure flow factors in the x-and y-direction as well as a shear flow factor in xdirection were implemented in the Reynolds Equation (2). The flow factors were determined according to the analytical equations of Patir and Cheng and implemented into the Reynolds equation.…”

“…Special surface texturing is not a new achievement; nature shows us a variety of geometries that can increase the tribological performance. For example, the special topography of fish skins allows for efficient movement [1,2], or the surfaces of plant leaves have evolved to be hydrophobic and self-cleaning, which is known as the lotus effect [3]. Around one fifth of worldwide energy consumption is caused by friction in tribological contacts [4].…”

Bionic research on Paramisgurnus dabryanus scales for drag reduction

“…Due to the exible deformation of loach's body, tiny scale distribution on the body surface, and the mucus retained on the scales, the DR performance of the loach is maximized. 25,26 Although the microstructure of the loach body surface triggers inspiration for the design of the bionic surface and has achieved some positive results on DR and anti-fouling, [27][28][29] further in-depth analysis on DR mechanisms is required and preparation of large-area microstructure for application is a challenge as well. In this study, the scale morphology of the loach was described, and the most appropriate structural characteristic parameters were selected.…”