Chapter 4 focuses on separated flows that occur in a variety of applications involving external flows, particularly related to aircraft, and internal flows, such as within turbomachines. Flow separation results when the flow does not have sufficient momentum to overcome an adverse pressure gradient, or when viscous dissipation occurs along the flow path. It is almost always associated with some form of aerodynamic penalty, including a loss of lift, an increase in drag, a loss of pressure recovery, and an increase in entropy. This chapter presents both passive and active methods to control these adverse effects.

Chapter 7 deals with 3-D laminar boundary-layer instabilities and their control. It covers the full range of Mach numbers from incompressible to hypersonic. A practical example of a 3-D boundary layer is the flow over a swept wing, which is susceptible to four types of instabilities that can lead to turbulence onset. Of these, cross-flow instability is the most dominant and therefore the most studied 3-D boundary-layer instability mechanism. A fundamental understanding of the instability has led to methods of control that have been successfully demonstrated at incompressible to hypersonic Mach numbers. These and other methods of control are presented.

Thoroughly revised and expanded, the new edition of this established textbook equips readers with a robust and practical understanding of experimental fluid mechanics. Enhanced features include improved support for students with emphasis on pedagogical instruction and self-learning, end-of-chapter summaries, 127 examples, 165 problems, refined illustrations, as well as new coverage of techniques in digital photography, frequency analysis of signals and the measurement of forces. It describes comprehensively classical and modern methods for flow visualisation and measuring flow rate, pressure, velocity, temperature, concentration, forces and wall shear stress, alongside supporting material on system response, measurement uncertainty, signal analysis, data analysis, optics, laboratory apparatus and laboratory practice. With enhanced instructor resources, including lecture slides, additional problems, laboratory support materials and online solutions, this is the ideal textbook for senior undergraduate and graduate students studying experimental fluid mechanics and is also suitable for an introductory measurements laboratory. Moreover, it is a valuable resource for practising engineers and scientists in this area.

Chapter 2 provides background on the types of flow sensors and actuators that are frequently used in fluid dynamics. The sensors are used to measure the mean (basic) flow that determines the relevant fluid instabilities. In addition, the sensors are used to document the flow conditions before and after flow control. Both passive and active flow control actuators are presented. These are demonstrated for different flow fields in subsequent chapters.

Chapter 10 considers a broad approach in which the application geometry that dictates the flow field is designed from the beginning, to enhance flow control. Examples include airfoil lift control without moving surfaces. This chapter presents a number of approaches. These range from a simple modification of a geometry to rigorous approaches that utilize an adjoint formulation of the Navier–Stokes equations that identifies sensitivity to changes in geometry and seeks those that maximize flow control authority.

Thoroughly revised and expanded, the new edition of this established textbook equips readers with a robust and practical understanding of experimental fluid mechanics. Enhanced features include improved support for students with emphasis on pedagogical instruction and self-learning, end-of-chapter summaries, 127 examples, 165 problems, refined illustrations, as well as new coverage of techniques in digital photography, frequency analysis of signals and the measurement of forces. It describes comprehensively classical and modern methods for flow visualisation and measuring flow rate, pressure, velocity, temperature, concentration, forces and wall shear stress, alongside supporting material on system response, measurement uncertainty, signal analysis, data analysis, optics, laboratory apparatus and laboratory practice. With enhanced instructor resources, including lecture slides, additional problems, laboratory support materials and online solutions, this is the ideal textbook for senior undergraduate and graduate students studying experimental fluid mechanics and is also suitable for an introductory measurements laboratory. Moreover, it is a valuable resource for practising engineers and scientists in this area.

Thoroughly revised and expanded, the new edition of this established textbook equips readers with a robust and practical understanding of experimental fluid mechanics. Enhanced features include improved support for students with emphasis on pedagogical instruction and self-learning, end-of-chapter summaries, 127 examples, 165 problems, refined illustrations, as well as new coverage of techniques in digital photography, frequency analysis of signals and the measurement of forces. It describes comprehensively classical and modern methods for flow visualisation and measuring flow rate, pressure, velocity, temperature, concentration, forces and wall shear stress, alongside supporting material on system response, measurement uncertainty, signal analysis, data analysis, optics, laboratory apparatus and laboratory practice. With enhanced instructor resources, including lecture slides, additional problems, laboratory support materials and online solutions, this is the ideal textbook for senior undergraduate and graduate students studying experimental fluid mechanics and is also suitable for an introductory measurements laboratory. Moreover, it is a valuable resource for practising engineers and scientists in this area.

Chapter 8 focuses on turbulent boundary layers. This considers a proposed autonomous cycle for turbulence production that results from an instability of a distorted mean flow near the wall surface that is produced by a spanwise array of coherent longitudinal vortices whose spacing scales with the viscous shear stress. The instability results in a lift-up and break-up of the longitudinal vortices that are linked to increased turbulence production and increased viscous drag. This and other mechanisms of turbulence production and viscous drag generation are presented. Methods of flow control that key on these specific mechanisms are presented along with significant results.

The multiscale nature of dispersed multiphase flows makes their characterization challenging. A single-phase flow may be reasonably characterized in terms of nondimensional parameters, such as the Reynolds number, Mach number, or Rayleigh number. But characterization of a multiphase flow requires additional parameters that describe the dispersed phase and its relation to the continuous phase. In this chapter we will introduce mathematical definitions of some basic quantities and explain how they characterize the dispersed multiphase flow.

The Euler–Euler (EE) approach derives its name from the fact that both the continuous and the dispersed phases are solved in the Eulerian frame of reference. For the fluid phase, the Eulerian frame is the natural choice and was pursued both in the particle-resolved (PR) and the Euler–Lagrange (EL) approaches. Particles are, however, inherently Lagrangian, and an Eulerian representation is possible only when the individual nature of the particles is erased. This requires that the particle-related Lagrangian quantities be suitably averaged, so that Eulerian fields of these quantities can be defined. The averaging process will allow particle volume fraction, particle velocity, and particle temperature fields to be defined as functions of space and time.

In this chapter, we investigate the problem of heat transfer from an isolated rigid sphere subjected to a cross flow of different temperature. This thermal problem is analogous to the flow problem considered earlier, and the interest here is to establish an expression for heat transfer in terms of the undisturbed ambient flow, which must now be characterized both in terms of relative velocity and temperature difference. We will start our investigation with rigorous analytical results in the Stokes and the small Péclet number regime.