4,956 research outputs found
Traveling Wave Fronts and Localized Traveling Wave Convection in Binary Fluid Mixtures
Nonlinear fronts between spatially extended traveling wave convection (TW)
and quiescent fluid and spatially localized traveling waves (LTWs) are
investigated in quantitative detail in the bistable regime of binary fluid
mixtures heated from below. A finite-difference method is used to solve the
full hydrodynamic field equations in a vertical cross section of the layer
perpendicular to the convection roll axes. Results are presented for
ethanol-water parameters with several strongly negative separation ratios where
TW solutions bifurcate subcritically. Fronts and LTWs are compared with each
other and similarities and differences are elucidated. Phase propagation out of
the quiescent fluid into the convective structure entails a unique selection of
the latter while fronts and interfaces where the phase moves into the quiescent
state behave differently. Interpretations of various experimental observations
are suggested.Comment: 46 pages, 11 figures. Accepted for publication in Phys. Rev.
Numerical Simulation of Convective-Radiative Heat Transfer
This book presents numerical, experimental, and analytical analysis of convective and radiative heat transfer in various engineering and natural systems, including transport phenomena in heat exchangers and furnaces, cooling of electronic heat-generating elements, and thin-film flows in various technical systems. It is well known that such heat transfer mechanisms are dominant in the systems under consideration. Therefore, in-depth study of these regimes is vital for both the growth of industry and the preservation of natural resources. The authors included in this book present insightful and provocative studies on convective and radiative heat transfer using modern analytical techniques. This book will be very useful for academics, engineers, and advanced students
Recent Contributions of Theory to Our Understanding of the Atlantic Meridional Overturning Circulation
Revolutionary observational arrays, together with a new generation of ocean and climate models, have provided new and intriguing insights into the Atlantic Meridional Overturning Circulation (AMOC) over the last two decades. Theoretical models have also changed our view of the AMOC, providing a dynamical framework for understanding the new observations and the results of complex models. In this paper we review recent advances in conceptual understanding of the processes maintaining the AMOC. We discuss recent theoretical models that address issues such as the interplay between surface buoyancy and wind forcing, the extent to which the AMOC is adiabatic, the importance of mesoscale eddies, the interaction between the middepth North Atlantic Deep Water cell and the abyssal Antarctic Bottom Water cell, the role of basin geometry and bathymetry, and the importance of a threeâdimensional multipleâbasin perspective. We review new paradigms for deep water formation in the highâlatitude North Atlantic and the impact of diapycnal mixing on vertical motion in the ocean interior. And we discuss advances in our understanding of the AMOC's stability and its scaling with largeâscale meridional density gradients. Along with reviewing theories for the mean AMOC, we consider models of AMOC variability and discuss what we have learned from theory about the detection and meridional propagation of AMOC anomalies. Simple theoretical models remain a vital and powerful tool for articulating our understanding of the AMOC and identifying the processes that are most critical to represent accurately in the next generation of numerical ocean and climate models
On the evolution of flow topology in turbulent Rayleigh-BĂ©nard convection
Copyright 2016 AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.Small-scale dynamics is the spirit of turbulence physics. It implicates many attributes of flow topology evolution, coherent structures, hairpin vorticity dynamics, and mechanism of the kinetic energy cascade. In this work, several dynamical aspects of the small-scale motions have been numerically studied in a framework of Rayleigh-Benard convection (RBC). To do so, direct numerical simulations have been carried out at two Rayleigh numbers Ra = 10(8) and 10(10), inside an air-filled rectangular cell of aspect ratio unity and pi span-wise open-ended distance. As a main feature, the average rate of the invariants of the velocity gradient tensor (Q(G), R-G) has displayed the so-calledPeer ReviewedPostprint (author's final draft
Second All-Union Seminar on Hydromechanics and Heat and Mass Exchange in Weightlessness, summaries of reports
Abstracts of reports are given which were presented at the Second All Union Seminar on Hydromechanics and Heat-Mass Transfer in Weightlessness. Topics include: (1) features of crystallization of semiconductor materials under conditions of microacceleration; (2) experimental results of crystallization of solid solutions of CDTE-HGTE under conditions of weightlessness; (3) impurities in crystals cultivated under conditions of weightlessness; and (4) a numerical investigation of the distribution of impurities during guided crystallization of a melt
NASA/MSFC FY88 Global Scale Atmospheric Processes Research Program Review
Interest in environmental issues and the magnitude of the environmental changes continues. One way to gain more understanding of the atmosphere is to make measurements on a global scale from space. The Earth Observation System is a series of new sensors to measure globally atmospheric parameters. Analysis of satellite data by developing algorithms to interpret the radiance information improves the understanding and also defines requirements for these sensors. One measure of knowledge of the atmosphere lies in the ability to predict its behavior. Use of numerical and experimental models provides a better understanding of these processes. These efforts are described in the context of satellite data analysis and fundamental studies of atmospheric dynamics which examine selected processes important to the global circulation
Non-Linear Lattice
The development of mathematical techniques, combined with new possibilities of computational simulation, have greatly broadened the study of non-linear lattices, a theme among the most refined and interdisciplinary-oriented in the field of mathematical physics. This Special Issue mainly focuses on state-of-the-art advancements concerning the many facets of non-linear lattices, from the theoretical ones to more applied ones. The non-linear and discrete systems play a key role in all ranges of physical experience, from macrophenomena to condensed matter, up to some models of space discrete space-time
2004 program of study : tides
The summer of 2004 saw the GFD program tackle âTidesâ. Myrl Hendershott (Scripps
Institution of Oceanography) gave a fabulous introduction to the subject in the first week
of the course, laying the foundations from astronomy and classical geophysical
fluid dynamics. In the second week, Chris Garrett (University of Victoria) admirably followed
up with recent developments on the subject, including the recent observations from satellite
altimetry, their implications to mixing and circulation, and even a memorable lecture on
the noble theme of how we might solve the world's energy crisis. The principal lectures
proved unusually popular this summer, and the seminar room at Walsh often overflowed in the
first two weeks.
Following on from the lectures, the seminar schedule of the summer covered in greater
detail the oceanographic issues with which researchers are actively grappling. We also
heard about related problems regarding atmospheric, planetary and stellar tides, together
with the usual mix of topics on GFD in general.
The summer once again featured a lecture for the general public in the Woods Hole
area. Carl Wunsch delivered a very well received lecture entitled âClimate Change Storiesâ,
in which he gave an impression of how scientists generally believe our climate is currently
changing, whilst simultaneously urging caution against some of the more outrageous and
exaggerated claims. The lecture was held at Lilly Auditorium, thanks to the hospitality
of the Marine Biology Laboratory. The reception following the lecture was enjoyed by
all.
Neil Balmforth and Stefan Llewellyn Smith acted as Co-Directors for the summer.
Janet Fields, Jeanne Fleming and Penny Foster provided the administrative backbone to
the Program, both during the summer and throughout the year beforehand. As always,
we were grateful to the Woods Hole Oceanographic Institution for the use of Walsh Cottage,
and Keith Bradley's solid service could not be overlooked. Shilpa Ghadge and Shreyas
Mandre are to be thanked for their part in comforting the fellows, developing the summer's
proceedings volume (available on the GFD web site) and for running the computer network.Funding was provided by the Office of Naval Research under Contract No. N00014-04-1-0157 and the National Science Foundation under Grant No. OCE-0325296
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