7,646 research outputs found
Superhydrophobic surfaces and their potential application to hydrodynamic drag reduction
No full textSuperhydrophobic surfaces appear frequently in the natural world, for example allowing insects to respire underwater and plants, such as the lotus leaf, to have self-cleaning properties. Attempts to mimic these superhydrophobic surfaces have been successful on nano- and micro-scales, with increased efficiency of water flowing through micro-channels when the walls are superhydrophobic. This thesis is focused on the proposed use of superhydrophobic surfaces to reduce drag on a much larger scale, applicable to small water craft such as canoes and yachts. The potential for drag reduction using superhydrophobic surfaces arises from the ability of such surfaces to retain an air-layer or plastron on the surface. The presence of a plastron results in slip and reduced shear at the surface, producing a drag reduction. This potential drag reduction is explored through numerical simulations and experimental testing. Computational Fluid Dynamics is used to explore the effect of slip on flow separation and viscous drag, allowing the potential drag reduction mechanisms to be explored. A range of superhydrophobic surfaces have been developed and characterised based on their roughness, contact angle and ability to retain a plastron. Confocal microscopy is used to generate the first high resolution 3D images of the air-water interface on a superhydrophobic surface over a large area. These images confirm the presence of a plastron on the surfaces and help contribute to the understanding of optimal design of superhydrophobic surfaces. These surfaces are explored experimentally in a towing tank with a repeatability of better than 1%. Refinement of the surface design leads to the presence of a plastron producing a relative drag reduction of up to 3% for hydrophobic sand, up to 10% for hydrophobic ridges and up to 15% for a hydrophobic mesh. Overall, superhydrophobic surfaces are shown to be capable of producing a relative drag reduction when a plastron is retained on the surface, although with the penalty of increased roughness-induced drag component. The drag reduction is shown to be linked to both the structure of the surface, and the quality and thickness of the plastron. It is demonstrated that it is difficult to retain a plastron over long immersion periods and manufacturing constraints currently limit applicability
Simulations of laminar flow past a superhydrophobic sphere with drag reduction and separation delay
No full textSuperhydrophobic surfaces have potential for reducing hydrodynamic drag by combining a structured surface and hydrophobicity to retain a lubricating air layer (plastron) at the surface. In the present contribution, numerical simulations of laminar flow past a superhydrophobic sphere are conducted using a two-phase flow representation. The results show drag reductions in Stokes flow of up to 19% for an air-water system, in agreement with previous analytic work, and demonstrate an increased effect as the Reynolds number is increased to 100. Drag reductions of up to 50% are achieved due to reduction in viscous drag and suppression of separation by the plastron, resulting in a narrower wake. To explore a less idealised model of the plastron, baffles have also been introduced to simulate the support of a plastron by roughness elements. The baffles lead to the attached vortex regime no longer being suppressed, but separation is delayed and drag reductions are evident in comparison to a solid sphere. Increasing the area solid fraction results in a diminished drag reduction due to the plastron, however drag reductions of up to 15% can still be achieved with solid fractions of 10%
Author Interview with Brian D. Anderson
No full textBrian D. Anderson was our feature artist of the week, October 19th - 23rd, 2020.https://jagworks.southalabama.edu/vid_presentations/1010/thumbnail.jp
Competition policy. by Brian Ellis
No full texttag=1 data=Competition policy. by Brian Ellis
tag=2 data=Ellis, Brian
tag=3 data=Australian Rationalist,
tag=5 data=46
tag=6 data=Autumn/Winter 1998
tag=7 data=51-56.
tag=8 data=ECONOMIC CONDITIONS
tag=9 data=COMPETITION%CORPORATISATION%NATIONAL COMPETITION POLICY%PRIVATE SECTOR PUBLIC SECTOR EFFECTIVENESS%SERVICE DELIVERY%SOCIAL POLICY%INNOVATION
tag=10 data=Examines the Government's National Competition Policy in relation to encouraging R&D, and the corporisation of public services and utilites. The author is Emeritus Professor of Philosophy at La Trobe UNiversity and Vice-President of the Rationalist Society of Australia. Article Taken from What's New.
tag=13 data=CABExamines the Government's National Competition Policy in relation to encouraging R&D, and the corporisation of public services and utilites. The author is Emeritus Professor of Philosophy at La Trobe UNiversity and Vice-President of the Rationalist Society of Australia. Article Taken from What's New
Art Behind Gaming: Brian D. Anderson
No full textA discussion with author Brian D. Anderson about worldbuilding in fantasy. Part of the Art Behind Gaming Online Con.https://jagworks.southalabama.edu/vid_presentations/1046/thumbnail.jp
In Honour of Brian MacWhinney: A Personal Account
No full textWhile this volume and the writings have made it amply clear what significant contributions Professor Brian MacWhinney has made to the field at large, in this afterword, we begin with a senior member of our author team (Ping Li, PL) followed by a mid-career member (Helen Zhao, HZ) and an early career member (Zhe Gao, ZG), to provide our personal accounts of Brian not only as a leading scholar but also as a role model who touches and changes people’s lives
Interview with Brian Alleyne, Sociologist Studying KDE
No full textA few months ago, the British journal Sociology published an article titled "Challenging Code: A Sociological Reading of the KDE Free Software Project". Eager to find out what a 'sociological reading' of KDE entails, Dot editor Oriol Mirosa rushed to contact the article's author, sociologist Brian Alleyne, who graciously and patiently agreed to be the subject of an interview
Understanding Author Rights
No full textAuthor Rights is the term used to describe a researcher\u27s rights related to their published work. In this session, Brian Young will: 1) provide an overview of author rights, 2) explain language often used in the publication agreement, and 3) demonstrate a tool (Sherpa Romeo) that can be used to quickly understand what default rights you have (and lose) when you publish with a specific journal
Shady trading on the rights market. by Brian Pollard
No full texttag=1 data=Shady trading on the rights market. by Brian Pollard
tag=2 data=Pollard, Brian
tag=3 data=New Doctor,
tag=6 data=Winter 1995
tag=7 data=11-12.
tag=8 data=EUTHANASIA
tag=10 data=Because the spotlight of public attention has been strongly focused on doctors in this debate, the author believes that it is essential that every doctor makes a clear distinction between his or her private views on the practice of euthanasia and its legislation, because the implications in each case are simply not comparable.
tag=11 data=1995/1/5
tag=12 data=95/0224
tag=13 data=CABBecause the spotlight of public attention has been strongly focused on doctors in this debate, the author believes that it is essential that every doctor makes a clear distinction between his or her private views on the practice of euthanasia and its legislation, because the implications in each case are simply not comparable
Letter from Brian Tatsuo to the friends of Michi Weglyn and the NCRR members present at the Tribute to Michi meetings
No full textA letter from Brian Tatsuo to the friends of Michi Weglyn and the NCRR members present at the Tribute to Michi meetings, in which offers a lengthy critique of the leadership of the National Coalition for Redress/Reparations (NCRR), with the exception of Frank Emi. In the letter he also refers to Weglyn as "the mother of the redress movement" and mentions that Frank Chin offered to organize a publicity plan for the event, but his help was refused.These materials are from box 73 and 74 of the Frank Chin Papers. The Frank Chin Papers contain personal and professional correspondence between Frank Chin and Michi Weglyn relating to particular projects on which either author was working as well as files related to the Day of Remembrance Tribute to Michi Weglyn
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