Study on the micro-dimpled surface in terms of drag performance

Paik, Bu‐Geun; Pyun, Young Sik; Kim, Kyung-Youl; Jung, Chul-Min; Kim, Chan-Gi

doi:10.1016/j.expthermflusci.2015.04.021

Cited by 9 publications

(3 citation statements)

References 20 publications

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“…Flow over a rough surface is known to display an early transition to turbulence, which means that a rough cylinder may have a lower drag coefficient than a smooth cylinder at a certain range of Reynolds numbers [3]. Different types of roughness pattern have been considered by previous researchers, for example dimples and grooves [2,3], surface trip wire [9,14], roughness strips [10], dimples [4,12], grooves [8,7,13], helical strakes [18], screened surface [11], and periodic blowing and suction [6], among others.…”

Section: Introductionmentioning

confidence: 98%

Control of flow past a dimpled circular cylinder

Zhou

Wang

Guo

et al. 2015

Experimental Thermal and Fluid Science

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Section: Introductionmentioning

confidence: 98%

Control of flow past a dimpled circular cylinder

Zhou

Wang

Guo

et al. 2015

Experimental Thermal and Fluid Science

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“…The study reported that for loads greater than 3 N, the friction gets reduced by about 75%. Paik et al 7 conducted an experimental study to determine the drag reduction on micro-dimpled surfaces fabricated with the help of ultrasonic nano-crystal surface modification. The authors reported that the micro-dimpled surfaces produced a better surface finish that resulted in drag reduction (3%-5%) consistently with a maximum drag reduction of 5.68%.…”

Section: Introductionmentioning

confidence: 99%

Studies on fabrication of protruded multi-shaped micro-feature array on AA 6063 by laser micromachining

Murugayan,

Chanda

et al. 2023

Journal of Micromanufacturing

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Miniaturization of parts of devices is the driving force for fabrication of micro-features. In this study fabrication of protruded multi-shaped micro-feature array on AA 6063 is attempted by laser micromachining. For fabricating the protruded microfeatures, the process parameters such as laser power, scanning speed and frequency of the laser beam have been optimized by considering track depth, width, and surface roughness as the output parameters. Three different cross sections in the tracks such as pileup section, W-section, and Gaussian groove section are observed. It is found that shape of the tracks vary with the scanning speed for the same power and frequency of the laser beam. The tracks of pileup section, W-section, and Gaussian groove section were produced for a laser scanning speed of 100 mm/s, 200mm/s, and 300 mm/s, respectively. Further, a laser-thermal ablative model is developed for predicting the depth of the single track and simulated using COMSOL® Multiphysics. The predicted track depths obtained from the simulations have good agreement with experimental results. In order to produce the protruded microfeatures of different shapes, multiple track analysis is done by fabricating the single tracks adjacent to one another by overlapping them, and the overlapping distance is optimized. The protruded microfeatures are then fabricated by removing the surrounding material for different scanning strategies and it is found that the contour strategy produced the features with minimal form error. Finally, it is demonstrated that an array of protruded micro-features of polygon (square, hexagon), and circular cross sections can be fabricated using the optimized process parameters for various applications.

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“…Given their friction-reducing nature, super-hydrophobic surfaces have great potential in the hydraulic engineering field, specially in the transport of water in pipes and in the marine industry (Fukuda et al, 2000;Yao et al, 2015;Moaven et al, 2013). The Reynolds number in these applications are in the turbulent range (>4,000) and studies of water flow on superhydrophobic surfaces obtained drag reduction in experiments with Re in the order of 10 3 (Daniello et al, 2009), 10 4 (Brassard et al, 2015) and 10 6 (Moaven et al, 2013;Paik et al, 2015;Yao et al, 2015) among others. In addition, the use of super-hydrophobic surfaces in offshore oil platforms reduces formation of ice and protects the platform, ship decks, antennas and locators of ships against erosion from sea water splashes and aerosols containing high concentration of salts (Boinovich et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Quantifying the Durability of a Friction-Reducing Surface with Recoverable Superhydrophobicity

et al. 2021

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The durability of super-hydrophobic surfaces in fully immersed conditions is a major obstacle to their application in engineering applications. We perform an experimental study to measure the friction factor f d as a function of time for a new super-hydrophobic surface that is capable of recovering the Cassie-Baxter wetting state. Values of f d were obtained by measuring the pressure drop and volume flux of a turbulent water flow in a 1.5 metre long duct containing one super-hydrophobic wall. The Reynolds number of the flow was approximately 4.5 × 10 4 for all experiments. Reductions in f d were 29-36 % relative to a hydraulically smooth surface. The Cassie-Baxter state could be recovered blowing air through the porous surface for 10 minutes. The durability of the drag-reduction, as quantified by the relaxation time T in which the surface loses its superhydrophobic characteristics, were measured to be between 10-60 minutes depending on the initial head. The relaxation time T was highly dependent on the pressure difference across the surface. In contrast to models based on Darcy flow through a porous medium, the study indicates that there seems to be a critical pressure difference beyond which the Cassie-Baxter state cannot be sustained for the material under consideration.

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Study on the micro-dimpled surface in terms of drag performance

Cited by 9 publications

References 20 publications

Control of flow past a dimpled circular cylinder

Control of flow past a dimpled circular cylinder

Studies on fabrication of protruded multi-shaped micro-feature array on AA 6063 by laser micromachining

Quantifying the Durability of a Friction-Reducing Surface with Recoverable Superhydrophobicity

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