Convective heat and mass transfer (Q2884968)

The book is devoted to the study of convective heat transfer in different physical situations where fluid flows occur and it evokes the mass transfer during these flows. It is divided into 13 chapters completed with 17 appendices.NEWLINENEWLINEChapter 1 gathers the physical conservation laws for mass, momentum and energy for fluids in Lagrangian or Eulerian frameworks. The case of multicomponent mixtures is treated as the book describes the cases of two or more chemical species in interaction in the flow. The diffusive mass transfer is explored in the case of mixtures of chemical species. Among different types of diffusion laws, the author focuses on Fick's law. Then, the chapter explains the boundary and interfacial conditions which may be considered at the surface of a wall or at the interface between different phases. The author uses gas-kinetic theory in order to compute some transport properties for mixtures of gases and gives some indications on the diffusion of mass in liquids mainly using the Stokes-Einstein expression of diffusivity.NEWLINENEWLINEChapter 2 explores some kinds of boundary layers which occur for a fluid flow near a surface. The author starts with a flat plate and describes the boundary-layer flow regimes which occur. He writes the laminar boundary-layer conservation laws using standard approximations and discusses the thickness of the laminar boundary layer. The chapter ends with the nondimensionalization of the conservation equations and the notion of similitude. This allows to introduce some famous dimensionless numbers which characterize the flow regimes.NEWLINENEWLINEIn Chapter 3, the author computes similarity solutions for laminar boundary layers. Starting with the boundary-layer mass and momentum equations, the author computes the expression of the Blasius similarity solution using an appropriate expression of the stream function. He then exploits the structure of this solution in order to derive some further properties of the flow under special conditions. The chapter continues with the case of a laminar flow past a wedge.NEWLINENEWLINEChapter 4 deals with laminar flows in channels or tubes. It starts with the description of Couette and Poiseuille flows, the author computes the displacement and the temperature using the simplifications induced by these two kinds of flows. He then considers a steady flow of an incompressible fluid and observes that two laminar duct flows may occur. In each case, he presents the appropriate computations which describe the variations of the corresponding physical quantities depending on the shape of the duct.NEWLINENEWLINEIn Chapter 5, the integral method is introduced which leads to approximate solutions of boundary-layer problems. The chapter starts with the integral momentum method where the author presents computations which lead to the ODE whose solution is the thickness of the boundary layer. The author solves this ODE in the cases of a laminar of a turbulent flow of an incompressible fluid under some conditions. The chapter then considers the energy integral method. Again, the corresponding ODE is solved for some parallel flows. The chapter ends with the description of approximate solutions for flows over axisymmetric bodies.NEWLINENEWLINEChapter 6 is the first one which is devoted to the study of turbulence. It starts with the description of the transition between laminar and turbulent flows, through the ranges of values of Reynold's number. Then, the author presents the averaging tools which simplify the resolution of the conservation equations. The notions of eddy viscosity and of eddy diffusivity are introduced and presented in some examples. In the case of a 2D turbulent flow on a flat surface, the author computes the approximate temperature and concentration on the wall under some assumptions and using Taylor expansion. The chapter ends with a short presentation of Kolmogorov's theory of small turbulent scales and with a description of flows past blunt bodies.NEWLINENEWLINEChapter 7 describes the properties of internal turbulent flows. Once again, the author starts with the description of the transition between laminar and turbulent flows. The hydrodynamics of turbulent duct flows are described, the author presents different models for the resolution of the corresponding equations in some particular cases. The heat transfer is computed for such flows and especially at the entrance of the duct.NEWLINENEWLINEThe short Chapter 8 describes the impact of transpiration of a flow through a wall, especially considering the induced variations of velocity, temperature and concentration profiles of the flow in the boundary layer. The chapter starts with the Couette flow film model, and the author computes the friction on the wall and the heat transfer. The chapter ends with the study of gas-liquid interphases.NEWLINENEWLINEChapter 9 analyzes the analogy among momentum, heat and mass transfer as the corresponding conservation equations look similar. This chapter describes six cases where such analogies may be observed and used in order to simplify the study of these equations.NEWLINENEWLINEThe long Chapter 10 describes the phenomenon of natural convection and different situations where such natural convection may occur. The author starts with the conservation equations for a 2D steady-state boundary-layer flow of a pure and Newtonian fluid. The author computes a nondimensionalization of these equations which introduces some specific numbers characterizing this phenomenon which is then described in lengthy details. The chapter progresses describing different situations where natural convection may occur: flat surface, vertical surface, inclined surface, submerged body, vertical flow passage, etc. The chapter ends with the analysis of natural convection caused by the combined thermal and mass diffusion effects. The purpose is here to compute solutions in different situations.NEWLINENEWLINEChapter 11 deals with mixed convection, that is, when forced and natural convections occur at the same time. The chapter starts with the laminar boundary-layer equations and with the introduction of Richardson's number \(Ri \) which characterizes the differences between forced convection (\(Ri\ll 1\)), natural convection (\(Ri\gg 1\)) and mixed convection (\(Ri\approx 1\)). The author computes a similarity solution for laminar flows and derives some properties of this solution, called correlations, in different situations which have been described in the previous chapters.NEWLINENEWLINEAs the fundamentals of turbulence have been described in the previous chapters starting with chapter 6, the author presents in Chapter 12 some models for turbulence. The Reynolds-averaged conservation equation is presented that the author couples with the eddy diffusivity in some 2D or 3D cases. The author explains how to build a model for turbulence starting from Navier-Stokes equations, then applying a time average tool. This leads to Reynolds-averaged Navier-Stokes (RANS) models with one-equation models. The general formulation of the \(K-\varepsilon \) model is then presented which leads to a two-equations model. The chapter then describes other models. The author presents some numerical simulations associated to these models in different contexts and the chapter ends with a brief description of computational fluid dynamics.NEWLINENEWLINEThe final chapter (Chapter 13) presents some properties of the flows in narrow channels, called here miniature channels, such as capillaries, microchannels, etc. The purpose of the chapter is to describe the limits of the classical analyses which can be used for standard channels and to propose some other tools. A clear description of the different situations is first presented in which the continuum approximation for fluid flows may be used or not, depending on the diameter of the channel and on the density of the fluid. The chapter then describes several slip flow regimes in different geometric situations. It ends with the description of a compressible flow in microchannels and that of a continuum flow in miniature flow passages.NEWLINENEWLINEThe 17 appendices present some further extensions of the notions which have been introduced in the main part of the book.NEWLINENEWLINEEach chapter contains many figures which illustrate the geometric situation under consideration, or the variables which are introduced, or results of computations. The many computations presented by the author are given in detail. Each chapter ends with many examples with solutions and with problems without solutions. Throughout the whole book, the author has thus made large pedagogical efforts in order to help the reader who tries to assimilate the different notions which are presented. The book will be useful for students who want to be acquainted with the thermodynamics of fluid flows and to researchers who will find here a complete survey of this science.