scholarly journals Discovery of riblets in a bird beak ( Rynchops ) for low fluid drag

2016 ◽  
Vol 374 (2073) ◽  
pp. 20160134 ◽  
Author(s):  
Samuel Martin ◽  
Bharat Bhushan
Keyword(s):  
Pressure Drop ◽  
Drag Reduction ◽  
Shear Stresses ◽  
Structured Surfaces ◽  
Mako Shark ◽  
Fluid Drag ◽  
Bird Beak ◽  
Modelling Studies ◽  
Flow Pressure ◽  
First Time

Riblet structures found on fast-swimming shark scales, such as those found on a mako shark, have been shown to reduce fluid drag. In previous experimental and modelling studies, riblets have been shown to provide drag reduction by lifting vortices formed in turbulent flow, decreasing overall shear stresses. Skimmer birds ( Rynchops ) are the only birds to catch fish in flight by flying just above the water surface with a submerged beak to fish for food. Because they need to quickly catch prey, reducing drag on their beak is advantageous. For the first time, riblet structures found on the beak of the skimmer bird have been studied experimentally and computationally for low fluid drag properties. In this study, skimmer replicas were studied for drag reduction through pressure drop in closed-channel, turbulent water flow. Pressure drop measurements are compared for black and yellow skimmer beaks in two configurations, and mako shark skin. In addition, two configurations of skimmer beak were modelled to compare drag properties and vortex structures. Results are discussed, and a conceptual model is presented to explain a possible drag reduction mechanism in skimmers. This article is part of the themed issue ‘Bioinspired hierarchically structured surfaces for green science’.

scholarly journals Analysis of Shark Skin Riblet Surfaces for Fluid Drag Reduction in Turbulent Flow Regime

2019 ◽  
Vol 9 (1S4) ◽  
pp. 666-668
Keyword(s):  
Fluid Flow ◽  
Flow Field ◽  
Turbulent Flow ◽  
Drag Reduction ◽  
Flow System ◽  
Shark Skin ◽  
Structured Surfaces ◽  
Turbulent Flow Regime ◽  
Fluid Drag ◽  
Fluid Drag Reduction

: The integument of fast swimming shark exhibits riblet inspired micro- structured surfaces oriented in the path of flow that will help to make lesser the wall drag in the tempestuous-flow system (turbulent flow). Design have been made for study and utilization, that has been recreate and refine as same as of the shark-skin riblets, presuming an extreme drag depletion of nearly 10% (percent). Mechanism of fluid drag in tempestuous flow and riblet drag depletion theories from experiments and simulations are examined. An examination of riblet intrepratation are discussed and the stellar riblet sizes are defined. An assessment of studies experimenting with riblets-topped shark scale replicas is also discussed. A method for preferring stellar riblet dimensions based on fluid-flow attributes is briefed and current manufacturing approaches are summarized. Due to the existence of little amounts of mucus/booger membranes on the integument of the shark, it is presumed that the constrained application of aqua phobic materials will recast the flow field around the riblets in some way favorable to the goals of augmented drag depletion

scholarly journals The effect of ultrafiltration transmembrane permeation on the flow field in a surrogate system of an artificial kidney

2021 ◽  
Vol 2 ◽  
Author(s):  
Matilde De Pascale ◽  
Monica Faria ◽  
Cristiana Boi ◽  
Viriato Semiao ◽  
Maria Norberta de Pinho
Keyword(s):  
Pressure Drop ◽  
Artificial Kidney ◽  
Shear Stresses ◽  
Removal Rates ◽  
Permeable Membrane ◽  
Fluid Removal ◽  
Renal Replacement Therapies ◽  
Extracorporeal Blood Circulation ◽  
Conventional Hemodialysis ◽  
Upper Chamber

Abstract Renal Replacement Therapies generally associated to the Artificial Kidney (AK) are membrane-based treatments that assure the separation functions of the failing kidney in extracorporeal blood circulation. Their progress from conventional hemodialysis towards high-flux hemodialysis (HFHD) through the introduction of ultrafiltration membranes characterized by high convective permeation fluxes intensified the need of elucidating the effect of the membrane fluid removal rates on the increase of the potentially blood-traumatizing shear stresses developed adjacently to the membrane. The AK surrogate consisting of two-compartments separated by an ultrafiltration membrane is set to have water circulation in the upper chamber mimicking the blood flow rates and the membrane fluid removal rates typical of HFHD. Pressure drop mirrors the shear stresses quantification and the modification of the velocities profiles. The increase on pressure drop when comparing flows in slits with a permeable membrane and an impermeable wall is ca. 512% and 576% for $ \mathrm{CA}22/5\%{\mathrm{SiO}}_2 $ and $ \mathrm{CA}30/5\%{\mathrm{SiO}}_2 $ membranes, respectively.

Pressure drop and drag reduction in two-phase non-newtonian slug flow

1976 ◽  
Vol 54 (1-2) ◽  
pp. 111-114 ◽  
Author(s):  
Lambert Otten ◽  
Abdelrahman S. Fayed
Keyword(s):  
Pressure Drop ◽  
Drag Reduction ◽  
Slug Flow ◽  
Two Phase

scholarly journals Mass Flow, Pressure Drop, and Leakage Dependent Modeling and Characterization of Solar Air Collectors

2014 ◽  
Vol 48 ◽  
pp. 250-263 ◽  
Author(s):  
Christian Welz ◽  
Christoph Maurer ◽  
Paolo Di Lauro ◽  
Gerhard Stryi-Hipp ◽  
Michael Hermann
Keyword(s):  
Pressure Drop ◽  
Mass Flow ◽  
Flow Pressure

Evaluation Analysis of Prediction Methods for Two-Phase Flow Pressure Drop in Mini-Channels

2008 ◽  
Author(s):  
Licheng Sun ◽  
Kaichiro Mishima
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Turbulent Region ◽  
Frictional Pressure Drop ◽  
New Correlation ◽  
Mini Channels ◽  
Flow Pressure ◽  
Better Than

2092 data of two-phase flow pressure drop were collected from 18 published papers of which the working fluids include R123, R134a, R22, R236ea, R245fa, R404a, R407C, R410a, R507, CO2, water and air. The hydraulic diameter ranges from 0.506 to 12mm; Relo from 10 to 37000, and Rego from 3 to 4×105. 11 correlations and models for calculating the two-phase frictional pressure drop were evaluated based upon these data. The results show that the accuracy of the Lockhart-Martinelli method, Mishima and Hibiki correlation, Zhang and Mishima correlation and Lee and Mudawar correalion in the laminar region is very close to each other, while the Muller-Steinhagen and Heck correlation is the best among the evaluated correlations in the turbulent region. A modified Chisholm correlation was proposed, which is better than all of the evaluated correlations in the turbulent region and its mean relative error is about 29%. For refrigerants only, the new correlation and Muller-Steinhagen and Heck correlation are very close to each other and give better agreement than the other evaluated correlations.

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