Effect of Slip on Flow Past Superhydrophobic Cylinders

Effect of Slip on Flow Past Superhydrophobic Cylinders
Author: Pranesh Muralidhar
Publisher:
Total Pages: 57
Release: 2012
Genre: Hydrophobic surfaces
ISBN:

Superhydrophobic surfaces are a class of surfaces that have a microscale roughness imposed on an already hydrophobic surface, akin to a lotus leaf. These surfaces have been shown to produce significant drag reduction for both laminar and turbulent flows of water through large and small-scale channels. The goal of this thesis was to explore how these surfaces alter the vortex shedding dynamics of a cylindrical body when coated on its surface, thus leading to an alteration in drag and lift on these surfaces. A cylindrical body was chosen as it is a very nice representative bluff body and sets the stage for predicting the behavior of hydrofoils and other bluff bodies under flow with a slip boundary condition. In this work, a series of experiments were performed which investigated the effect of superhydrophobic-induced slip on the flow past a circular cylinder. In these experiments, circular cylinders were coated with a series of superhydrophobic surfaces fabricated from PDMS with well-defined micron-sized patterns of surface roughness or random slip surfaces fabricated by sanding Teflon cylinders or spray painting superhydrophobic paint on a smooth cylinder. The presence of the superhydrophobic surface was found to have a significant effect on the vortex shedding dynamics in the wake of the circular cylinder. When compared to a smooth, no-slip cylinder, cylinders coated with superhydrophobic surfaces were found to delay the onset of vortex shedding and increase the length of the recirculation region in the wake of the cylinder. For superhydrophobic surfaces with ridges aligned in the flow direction the separation point was found to move further upstream towards the front stagnation point of the cylinder and the vortex shedding frequency was found to increase. For superhydrophobic surfaces with ridges running normal to the flow direction, the separation point and shedding frequency trends were reversed. The vortices shed from these surfaces were found to be weaker and less interlaced leading to reduced circulation and lift forces on these cylinders. The effect of slip on bluff bodies and separating flow was dealt with in detail in this thesis and the results could be used to predict the impact of these surfaces on the flow past hydrofoils which combine skin friction dominated flow with separating flow.

Advances in Contact Angle, Wettability and Adhesion

Advances in Contact Angle, Wettability and Adhesion
Author: K. L. Mittal
Publisher: John Wiley & Sons
Total Pages: 348
Release: 2019-10-16
Genre: Technology & Engineering
ISBN: 1119592550

This is the fourth volume in the series "Advances in Contact Angle, Wettability and Adhesion" initiated to consolidate information and provide commentary on certain recent research aspects dealing with this important topic. Its predecessor Volumes 1, 2 and 3 were published in 2013, 2015 and 2018 respectively. This new book comprising 14 research and review articles is divided into four parts: Part 1: Contact Angle and Wettability Aspects; Part 2: Surface Free Energy and Surface Tension Determination; Part 3: Applied Aspects. The topics covered include: Contact Angle Determination of Talc Powders from Heat of Immersion Surface Wetting at Macro and Nanoscale Wettability of Wood Surfaces with Waterborne Acrylic Lacquer Stains Modulated by DBD Plasma Treatment in Air at Atmospheric Pressure Wettability of Ultrafiltration Membranes Determination of the Surface Free Energy of Solid Surfaces: Can the Best Model be Found Surface Free Energy Characterization of Talc Powders Determination of the Surface Free Energy of Skin and the Factors Affecting it by the Contact Angle Method Determination of Surface Tension Components of Aqueous Solutions using Fomblin HC/25 R Perfluoropolyether Liquid Film as a Solid Substrate Enhancing the Wettability of Polybenzimidazole (PBI) to Improve Fuel Cell Performance Evaluation of Sebum Resistance for Long-Wear Face Make-Up Products Using Contact Angle Measurements Contact Angle Hysteresis of Pressure-Sensitive Adhesives due to Adhesion Tension Relaxation The Potential of Surface Nano-Engineering and Superhydrophobic Surfaces in Drag Reduction Laser Surface Engineering of Polymeric Materials for Enhanced Mesenchymal Stem Cell Adhesion and Growth Sisal-Green Resin Interfaces in Green Composites.

Proceedings of the 5th International Conference on Jets, Wakes and Separated Flows (ICJWSF2015)

Proceedings of the 5th International Conference on Jets, Wakes and Separated Flows (ICJWSF2015)
Author: Antonio Segalini
Publisher: Springer
Total Pages: 603
Release: 2016-07-18
Genre: Technology & Engineering
ISBN: 3319306022

This volume collects various contributions from the 5th International Conference on Jets, Wakes and Separated Flows (ICJWSF2015) that took place in Stockholm during June 2015. Researchers from all around the world presented their latest results concerning fundamental and applied aspects of fluid dynamics. With its general character, the conference embraced many aspects of fluid dynamics, such as shear flows, multiphase flows and vortex flows, for instance. The structure of the present book reflects the variety of topics treated within the conference i.e. Jets, Wakes, Separated flows, Vehicle aerodynamics, Wall-bounded and confined flows, Noise, Turbomachinery flows, Multiphase and reacting flows, Vortex dynamics, Energy-related flows and a section dedicated to Numerical analyses.

Applied Continuum Mechanics for Thermo-Fluids

Applied Continuum Mechanics for Thermo-Fluids
Author: Jafar Ghazanfarian
Publisher: CRC Press
Total Pages: 246
Release: 2024-06-21
Genre: Science
ISBN: 1040026338

Applied Continuum Mechanics for Thermo-Fluids presents the tensor notation rules and integral theorems before defining the preliminary concepts and applications of continuum mechanics. It bridges the gap between physical concepts and mathematical expressions with a rigorous mathematical treatment. After discussing fundamental concepts of continuum mechanics, the text explains basic subjects such as the Stokes hypothesis, the second coefficient of viscosity, non-Newtonian fluids, non-symmetric stress tensor, and the full Navier-Stokes equation. With coverage of interdisciplinary topics, the book highlights issues such as relativistic fluid mechanics, stochastic mechanics, fractional calculus, nanoscale fluid mechanics, polar fluids, electrodynamics, and traffic flows. It describes fundamental concepts of vorticity dynamics, including the definition of vorticity and circulation, with corresponding balance equations and related theorems. This text is intended for upper-level undergraduate and postgraduate mechanical, chemical, aerospace, civil engineering, and physics students taking continuum mechanics, advanced fluid mechanics, convective heat transfer, turbulence, or any other similar courses. In addition, this book can be an excellent resourec for scientists who want to trigger research on topics related to thermo-fluids. Instructors will be able to utilize a Solutions Manual and Figure Slides for their course.

Flow Control Techniques and Applications

Flow Control Techniques and Applications
Author: Jinjun Wang
Publisher: Cambridge University Press
Total Pages: 293
Release: 2019
Genre: Science
ISBN: 1107161568

Master the theory, applications and control mechanisms of flow control techniques.

Introduction to Theoretical and Computational Fluid Dynamics

Introduction to Theoretical and Computational Fluid Dynamics
Author: Constantine Pozrikidis
Publisher: Oxford University Press
Total Pages: 1274
Release: 2011-11-17
Genre: Computers
ISBN: 0199752079

This book discusses the fundamental principles and equations governing the motion of incompressible Newtonian fluids, and simultaneously introduces numerical methods for solving a broad range of problems. Appendices provide a wealth of information that establishes the necessary mathematical and computational framework.

Flow Visualization in Materials Processing

Flow Visualization in Materials Processing
Author: Tomomasa Uemura
Publisher: Springer
Total Pages: 225
Release: 2017-10-05
Genre: Technology & Engineering
ISBN: 4431565671

This book presents a comprehensive review of particle image velocimetry (PIV) and particle tracking velocimetry (PTV) as tools for experimental fluid dynamics (EFD). It shares practical techniques for high-speed photography to accurately analyze multi-phase flows; in particular, it addresses the practical know-how involved in high-speed photography, including e.g. the proper setup for lights and illumination; optical systems to remove perspective distortion; and the density of tracer particles and their fluorescence in the context of PIV and PTV. In this regard, using the correct photographic technique plays a key role in the accurate analysis of the respective flow. Practical applications include bubble and liquid flow dynamics in materials processes agitated by gas injection at high temperatures, mixing phenomena due to jet-induced rotary sloshing, and wettability effects on the efficiency of the processes.

Solving Problems in Multiply Connected Domains

Solving Problems in Multiply Connected Domains
Author: Darren Crowdy
Publisher: SIAM
Total Pages: 456
Release: 2020-04-20
Genre: Mathematics
ISBN: 1611976154

Whenever two or more objects or entities—be they bubbles, vortices, black holes, magnets, colloidal particles, microorganisms, swimming bacteria, Brownian random walkers, airfoils, turbine blades, electrified drops, magnetized particles, dislocations, cracks, or heterogeneities in an elastic solid—interact in some ambient medium, they make holes in that medium. Such holey regions with interacting entities are called multiply connected. This book describes a novel mathematical framework for solving problems in two-dimensional, multiply connected regions. The framework is built on a central theoretical concept: the prime function, whose significance for the applied sciences, especially for solving problems in multiply connected domains, has been missed until recent work by the author. This monograph is a one-of-a-kind treatise on the prime function associated with multiply connected domains and how to use it in applications. The book contains many results familiar in the simply connected, or single-entity, case that are generalized naturally to any number of entities, in many instances for the first time. Solving Problems in Multiply Connected Domains is aimed at applied and pure mathematicians, engineers, physicists, and other natural scientists; the framework it describes finds application in a diverse array of contexts. The book provides a rich source of project material for undergraduate and graduate courses in the applied sciences and could serve as a complement to standard texts on advanced calculus, potential theory, partial differential equations and complex analysis, and as a supplement to texts on applied mathematical methods in engineering and science.