Rayleigh-B‚nard Convection


Book Description

This invaluable book presents a concise but systematic account of the formation of spatial flow structures in a horizontal fluid layer heated from below. Flows of this type, known as Rayleigh-B‚nard convection, show important features of behaviour inherent not only in various hydrodynamic-instability phenomena but also in nonlinear pattern-forming processes in other contexts. The book describes the basic methods of investigating convection patterns, and the types of two- and three-dimensional flows, pattern defects, and sequences of convection-regime changes.The author pays special attention to the question of how various factors (mainly reducible to initial and boundary conditions) determine the shapes and sizes of the structures which develop. In this way, the role of order and disorder in flow patterns, as a factor strongly affecting the character of the evolution of structures, is revealed. The presentation emphasizes the physical picture of these phenomena, without excessive mathematical detail.




Upper Bounds on the Heat Transport in Rayleigh-Benard Convection


Book Description

We study the scaling of bounds on heat transport in Rayleigh-Benard convection of a layer of fluid between two infinite horizontal plates under various thermal boundary conditions. First we demonstrate how to establish an upper bound on the heat transport, measured by the Nusselt number Nu, as a function of the Rayleigh number Ra, using the Doering-Constantin approach of background profiles. Then we numerically compute the bounds using optimal piecewise linear background profiles. For each boundary condition we find that the Nu is bounded above by a constant C times the square root of Ra. In the fixed temperature case, we get C = 0.045; in the fixed flux case, we get C = 0.078; while for general thermal boundary conditions, we find numerically that the prefactor C is similar to that in the fixed flux case, and depends, at best, weakly on the Biot number.




Convection in Rotating Fluids


Book Description

Spatial inhomogeneity of heating of fluids in the gravity field is the cause of all motions in nature: in the atmosphere and the oceans on Earth, in astrophysical and planetary objects. All natural objects rotate and convective motions in rotating fluids are of interest in many geophysical and astrophysical phenomena. In many industrial applications, too (crystal growth, semiconductor manufacturing), heating and rotation are the main mechanisms defining the structure and quality of the material. Depending on the geometry of the systems and the mutual orientation of temperature and gravity field, a variety of phenomena will arise in rotating fluids, such as regular and oscillating waves, intensive solitary vortices and regular vortex grids, interacting vortices and turbulent mixing. In this book the authors elucidate the physical essence of these phenomena, determining and classifying flow regimes in the space of similarity numbers. The theoretical and computational results are presented only when the results help to explain basic qualitative motion characteristics. The book will be of interest to researchers and graduate students in fluid mechanics, meteorology, oceanography and astrophysics, crystallography, heat and mass transfer.




Internally Heated Convection and Rayleigh-Bénard Convection


Book Description

This Brief describes six basic models of buoyancy-driven convection in a fluid layer: three configurations of internally heated convection and three configurations of Rayleigh-Bénard convection. The author discusses the main quantities that characterize heat transport in each model, along with the constraints on these quantities. This presentation is the first to place the various models in a unified framework, and similarities and differences between the cases are highlighted. Necessary and sufficient conditions for convective motion are given. For the internally heated cases only, parameter-dependent lower bounds on the mean fluid temperature are proven, and results of past simulations and laboratory experiments are summarized and reanalyzed. The author poses several open questions for future study.




Magnetoconvection


Book Description

Leading experts present the current state of knowledge of the subject of magnetoconvection from the viewpoint of applied mathematics.




Direct and Large Eddy Simulation XII


Book Description

This book gathers the proceedings of the 12th instalment in the bi-annual Workshop series on Direct and Large Eddy Simulation (DLES), which began in 1994 and focuses on modern techniques used to simulate turbulent flows based on the partial or full resolution of the instantaneous turbulent flow structure. With the rapidly expanding capacities of modern computers, this approach has attracted more and more interest over the years and will undoubtedly be further enhanced and applied in the future. Hybrid modelling techniques based on a combination of LES and RANS approaches also fall into this category and are covered as well. The goal of the Workshop was to share the state of the art in DNS, LES and related techniques for the computation and modelling of turbulent and transitional flows. The respective papers highlight the latest advances in the prediction, understanding and control of turbulent flows in academic and industrial applications.




Heat Generation and Transport in the Earth


Book Description

Heat provides the energy that drives almost all geological phenomena and sets the temperature at which these phenomena operate. This book explains the key physical principles of heat transport with simple physical arguments and scaling laws that allow quantitative evaluation of heat flux and cooling conditions in a variety of geological settings and systems. The thermal structure and evolution of magma reservoirs, the crust, the lithosphere and the mantle of the Earth are reviewed within the context of plate tectonics and mantle convection - illustrating how theoretical arguments can be combined with field and laboratory data to arrive at accurate interpretations of geological observations. Appendices contain data on the thermal properties of rocks, surface heat flux measurements and rates of radiogenic heat production. This book can be used for advanced courses in geophysics, geodynamics and magmatic processes, and is a reference for researchers in geoscience, environmental science, physics, engineering and fluid dynamics.







Bénard Cells and Taylor Vortices


Book Description

This book describes the motions resulting from heating a fluid layer from below.