Turbulent Drag Reduction by Surfactant Additives

Turbulent Drag Reduction by Surfactant Additives
Author: Feng-Chen Li
Publisher: John Wiley & Sons
Total Pages: 233
Release: 2012-01-10
Genre: Science
ISBN: 1118181115

Turbulent drag reduction by additives has long been a hot research topic. This phenomenon is inherently associated with multifold expertise. Solutions of drag-reducing additives are usually viscoelastic fluids having complicated rheological properties. Exploring the characteristics of drag-reduced turbulent flows calls for uniquely designed experimental and numerical simulation techniques and elaborate theoretical considerations. Pertinently understanding the turbulent drag reduction mechanism necessities mastering the fundamentals of turbulence and establishing a proper relationship between turbulence and the rheological properties induced by additives. Promoting the applications of the drag reduction phenomenon requires the knowledge from different fields such as chemical engineering, mechanical engineering, municipal engineering, and so on. This book gives a thorough elucidation of the turbulence characteristics and rheological behaviors, theories, special techniques and application issues for drag-reducing flows by surfactant additives based on the state-of-the-art of scientific research results through the latest experimental studies, numerical simulations and theoretical analyses. Covers turbulent drag reduction, heat transfer reduction, complex rheology and the real-world applications of drag reduction Introduces advanced testing techniques, such as PIV, LDA, and their applications in current experiments, illustrated with multiple diagrams and equations Real-world examples of the topic’s increasingly important industrial applications enable readers to implement cost- and energy-saving measures Explains the tools before presenting the research results, to give readers coverage of the subject from both theoretical and experimental viewpoints Consolidates interdisciplinary information on turbulent drag reduction by additives Turbulent Drag Reduction by Surfactant Additives is geared for researchers, graduate students, and engineers in the fields of Fluid Mechanics, Mechanical Engineering, Turbulence, Chemical Engineering, Municipal Engineering. Researchers and practitioners involved in the fields of Flow Control, Chemistry, Computational Fluid Dynamics, Experimental Fluid Dynamics, and Rheology will also find this book to be a much-needed reference on the topic.

Turbulent Drag Reduction Using Compliant Coatings

Turbulent Drag Reduction Using Compliant Coatings
Author:
Publisher:
Total Pages: 0
Release: 2002
Genre:
ISBN:

An experimental study was carried in a water tunnel, where the drag of several compliant coatings in the turbulent boundary layer was measured. An axi-symmetric test model similar to that used by NUWC was designed and built, and identical compliant coatings were tested as a part of collaboration between UK, U.S. and Russia. While experimental results in the UK show small drag reductions by up to 3% in some of the compliant coatings tested, skin-friction drags of compliant coatings measured at MIT are consistently greater than that of rigid surface. The Russian data are not yet available at the time of writing this report. The aging of the compliant coatings are thought to be the reason for these discrepancies. A better coordination will be required for the rest of the program to overcome this problem.

Turbulent Drag Reduction Using Micro and Nanotextured Ultrahydrophobic Surfaces

Turbulent Drag Reduction Using Micro and Nanotextured Ultrahydrophobic Surfaces
Author:
Publisher:
Total Pages: 17
Release: 2010
Genre:
ISBN:

This final report documents the findings of our research project which demonstrated through a combination of experimental measurements and numerical simulations that ultrahydrophobic surfaces can be used to delay the transition to turbulence and dramatically reduce drag in both external and internal turbulent flows. These enhancements should have a profound effect on a huge variety of existing technologies, resulting in benefits ranging from a reduction in the pressure drop in pipe flows to an increase in speed and efficiency in surface ships and small submersible vehicles.

Turbulent Drag Reduction Research

Turbulent Drag Reduction Research
Author: D. M. Bushnell
Publisher:
Total Pages: 13
Release: 1984
Genre:
ISBN:

This paper summarizes recent NASA research in the area of turbulent drag reduction for attached flows. The most promising passive techniques utilize non-planar geometry and indicate a possible combined net performance on the order of 20 percent. Of particular interest is the suitability of these devices for retrofit of existing vehicles. Research to optimize an active system involving tangential slot injection of low momentum (LFC) air indicates that free shear layers which are initially turbulent can be favorably controlled through use of rigid plates (large eddy-breakup devices). More conventional flow control approaches -- such as narrow-band acoustic inputs -- are evidently not effective for free mixing regions imbedded in thick turbulent layers. Experiments indicate that high frequency forcing of Emmons spots in the initial transition region to create small scale motions provides localized drag reductions, but net reductions are not yet available due to the high levels of forcing energy required.

A Century of Innovation

A Century of Innovation
Author: 3M Company
Publisher: 3m Company
Total Pages: 246
Release: 2002
Genre: 3M Company
ISBN:

A compilation of 3M voices, memories, facts and experiences from the company's first 100 years.

Flowing Matter

Flowing Matter
Author: Federico Toschi
Publisher: Springer Nature
Total Pages: 309
Release: 2019-09-25
Genre: Science
ISBN: 3030233707

This open access book, published in the Soft and Biological Matter series, presents an introduction to selected research topics in the broad field of flowing matter, including the dynamics of fluids with a complex internal structure -from nematic fluids to soft glasses- as well as active matter and turbulent phenomena. Flowing matter is a subject at the crossroads between physics, mathematics, chemistry, engineering, biology and earth sciences, and relies on a multidisciplinary approach to describe the emergence of the macroscopic behaviours in a system from the coordinated dynamics of its microscopic constituents. Depending on the microscopic interactions, an assembly of molecules or of mesoscopic particles can flow like a simple Newtonian fluid, deform elastically like a solid or behave in a complex manner. When the internal constituents are active, as for biological entities, one generally observes complex large-scale collective motions. Phenomenology is further complicated by the invariable tendency of fluids to display chaos at the large scales or when stirred strongly enough. This volume presents several research topics that address these phenomena encompassing the traditional micro-, meso-, and macro-scales descriptions, and contributes to our understanding of the fundamentals of flowing matter. This book is the legacy of the COST Action MP1305 “Flowing Matter”.