Turbulent Flow Over a Superhydrophobic Surface with Isotropic Slip

Turbulent Flow Over a Superhydrophobic Surface with Isotropic Slip
Author: Babak Vajdi Hokmabad
Publisher:
Total Pages: 107
Release: 2015
Genre: Hydrophobic surfaces
ISBN:

Superhydrophobic surfaces are proven to be capable of reducing the skin friction in laminar and turbulent flows. These surfaces consist of micro/nano-scale hydrophobic roughness features which make the surface render a non-wetting property due to the entrainment of air pockets between the solid surface and the liquid phase. This shear free air-water interface reduces the frictional drag force. This flow control method has two distinct effects in turbulent flow: drag reduction due to effective slip velocity and drag reduction associated with the modification of the turbulent flow structures (Rastegari & Akhavan, 2015). In the current research, the turbulent structure of the inner layer of a turbulent channel flow over a non-wetted superhydrophobic (SHO) surface with random pattern is experimentally studied. The results are compared with the wetted counterpart and also a smooth reference surface. Two planar particle image velocimetry (PIV) measurements are carried out in the streamwise/spanwise and streamwise/wall-normal planes. The vector fields are obtained from both ensemble averaging and individual cross-correlations of double-frame PIV images. The results showed a small increase (~5%) of the mean velocity profile at y+=10 over the non-wetted surface in comparison with the wetted and the smooth surfaces. Up to 15% reduction of normal and shear Reynolds stresses is observed in the inner layer over the non-wetted SHO surface. The wetted SHO counterpart demonstrates no effect on the mean velocity and Reynolds stresses in comparison with the smooth surface implying that the surface is hydrodynamically smooth. A noticeable suppression of the sweep and ejection events, increase of the spanwise spacing of the low and high speed streaks, and attenuation of vortical structures are observed over the non-wetted SHO. These indicate attenuation of the turbulence regeneration cycle due to the slip boundary condition over the non- iii wetted SHO surfaces with random texture. Tomographic PIV (tomo-PIV) and 3D particle tracking velocimetry (3D-PTV) as three-dimensional flow measurement techniques can unravel the relevant physics by revealing the flow modifications across the third dimension. The performance of these measurements is evaluated through comparison with DNS data in the literature. The results show that 3D-PTV is more accurate compared to tomo-PIV especially in near-wall region where noise increases for all PIV measurements.

Superhydrophobic Surfaces

Superhydrophobic Surfaces
Author: Russell J. Crawford
Publisher: Elsevier
Total Pages: 181
Release: 2015-02-19
Genre: Technology & Engineering
ISBN: 0128013311

Superhydrophobic Surfaces analyzes the fundamental concepts of superhydrophobicity and gives insight into the design of superhydrophobic surfaces. The book serves as a reference for the manufacturing of materials with superior water-repellency, self-cleaning, anti-icing and corrosion resistance. It thoroughly discusses many types of hydrophobic surfaces such as natural superhydrophobic surfaces, superhydrophobic polymers, metallic superhydrophobic surfaces, biological interfaces, and advanced/hybrid superhydrophobic surfaces. - Provides an adequate blend of complex engineering concepts with in-depth explanations of biological principles guiding the advancement of these technologies - Describes complex ideas in simple scientific language, avoiding overcomplicated equations and discipline-specific jargon - Includes practical information for manufacturing superhydrophobic surfaces - Written by experts with complementary skills and diverse scientific backgrounds in engineering, microbiology and surface sciences

Non-wettable Surfaces

Non-wettable Surfaces
Author: Robin H A Ras
Publisher: Royal Society of Chemistry
Total Pages: 406
Release: 2016-11-21
Genre: Science
ISBN: 1782623957

The objective of this book is to integrate information about the theory, preparation and applications of non-wettable surfaces in one volume. By combining the discussion of all three aspects together the editors will show how theory assists the development of preparations methods and how these surfaces can be applied to different situations. The book is separated into three sections, first covering the theory, then going on to preparation of these surfaces and finally discussing the applications in detail. Edited by two of the most innovative contributors to the field of superhydrophobicity, this book will be essential reading for materials scientists interested in any aspect of surface, colloid and polymer science, thermodynamics, superhydrophobic and superhygrophobic surfaces.

Laser-Induced Periodic Surface Nano- and Microstructures for Tribological Applications

Laser-Induced Periodic Surface Nano- and Microstructures for Tribological Applications
Author: Jörn Bonse
Publisher: MDPI
Total Pages: 190
Release: 2020-11-25
Genre: Technology & Engineering
ISBN: 303943523X

This book is the printed edition of the Special Issue published in Materials. The book provides an overview of current international research activities in the field of friction and wear management through the laser processing of periodic surface micro- and nanostructures for technical and medical applications. Contributions of renowned scientists from academia and industry provide a bridge between the fields of tribology and laser material processing in order to foster current knowledge and present new ideas for future applications and new technologies.

Bioinspired Structures and Design

Bioinspired Structures and Design
Author: Wole Soboyejo
Publisher: Cambridge University Press
Total Pages: 374
Release: 2020-09-17
Genre: Technology & Engineering
ISBN: 1108963447

Master simple to advanced biomaterials and structures with this essential text. Featuring topics ranging from bionanoengineered materials to bio-inspired structures for spacecraft and bio-inspired robots, and covering issues such as motility, sensing, control and morphology, this highly illustrated text walks the reader through key scientific and practical engineering principles, discussing properties, applications and design. Presenting case studies for the design of materials and structures at the nano, micro, meso and macro-scales, and written by some of the leading experts on the subject, this is the ideal introduction to this emerging field for students in engineering and science as well as researchers.

Applied Mathematics, Modeling and Computer Simulation

Applied Mathematics, Modeling and Computer Simulation
Author: C.-H. Chen
Publisher: IOS Press
Total Pages: 1154
Release: 2022-02-25
Genre: Computers
ISBN: 1643682555

The pervasiveness of computers in every field of science, industry and everyday life has meant that applied mathematics, particularly in relation to modeling and simulation, has become ever more important in recent years. This book presents the proceedings of the 2021 International Conference on Applied Mathematics, Modeling and Computer Simulation (AMMCS 2021), hosted in Wuhan, China, and held as a virtual event from 13 to 14 November 2021. The aim of the conference is to foster the knowledge and understanding of recent advances across the broad fields of applied mathematics, modeling and computer simulation, and it provides an annual platform for scholars and researchers to communicate important recent developments in their areas of specialization to colleagues and other scientists in related disciplines. This year more than 150 participants were able to exchange knowledge and discuss recent developments via the conference. The book contains 115 peer-reviewed papers, selected from more than 250 submissions and ranging from the theoretical and conceptual to the strongly pragmatic and all addressing industrial best practice. Topics covered include mathematical modeling and applications, engineering applications and scientific computations, and the simulation of intelligent systems. Providing an overview of recent development and with a mix of practical experiences and enlightening ideas, the book will be of interest to researchers and practitioners everywhere.

The Lattice Boltzmann Equation

The Lattice Boltzmann Equation
Author: S. Succi
Publisher: Oxford University Press
Total Pages: 308
Release: 2001-06-28
Genre: Mathematics
ISBN: 9780198503989

Certain forms of the Boltzmann equation, have emerged, which relinquish most mathematical complexities of the true Boltzmann equation. This text provides a detailed survey of Lattice Boltzmann equation theory and its major applications.