This book describes and explains the fundamental physical processes involved in bubble dynamics and the phenomenon of cavitation. It is intended as a combination of a reference book for those scientists and engineers who work with cavitation or bubble dynamics and as a monograph for advanced students interested in some of the basic problems associated with this category of multiphase flows. A basic knowledge of fluid flow and heat transfer is assumed but otherwise the analytical methods presented are developed from basic principles.

The book begins with a chapter on nucleation and describes both the theory and observations of nucleation in flowing and non-flowing systems. The following three chapters provide a systematic treatment of the dynamics of the growth, collapse or oscillation of individual bubbles in otherwise quiescent liquids. Chapter 4 summarizes the state of knowledge of the motion of bubbles in liquids. Chapter 5 describes some of the phenomena which occur in homogeneous bubbly flows with particular emphasis on cloud cavitation and this is followed by a chapter summarizing some of the experiemntal observations of cavitating flows. The last chapter provides a review of the free streamline methods used to treat separated cavity flows with large attached cavities.

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Cavitation and Bubble Dynamics

The boundary layer equations for plane, incompressible, and steady flow are 

$$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Boundary Layer Theory

A front-tracking method for the computations of multiphase flow

Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves

This review discusses the use of the combination of surface roughness and hydrophobicity for engineering large slip at the fluid-solid interface. These superhydrophobic surfaces were initially inspired by the unique water-repellent properties of the lotus leaf and can be employed to produce drag reduction in both laminar and turbulent flows, enhance mixing in laminar flows, and amplify diffusion-osmotic flows. We review the current state of experiments, simulations, and theory of flow past superhydrophobic surfaces. In addition, the designs and limitations of these surfaces are discussed, with an eye toward implementing these surfaces in a wide range of applications.

Slip on Superhydrophobic Surfaces

Perturbed Partial Cavity Drag Reduction at High Reynolds Numbers

We propose a new iterative X-ray computed tomography (CT) reconstruction algorithm for electron beam X-ray tomography of multiphase flows in metal pipes. This application uses limited-angle projections due to the fixed configuration, and semiconductor-type energy-integrating detectors. For the data-fitting objective function, the proposed method incorporates a nonlinear Gaussian model with object-dependent variance to approximate the compound Poisson distribution, and a dual material decomposition based on images of the volume fractions of metal (titanium) and liquid (water). The volume fraction-based material decomposition enables us to use a maximum sum constraint that helps address the ill-posed nature of the problem. Two different regularizers, $\ell _0$ norm and edge-preserving hyperbola regularizers, are applied differently on each volume fraction image based on the characteristics of objects in each image. A synthetic phantom simulation illustrates that the proposed algorithm enables the aforementioned CT system to achieve high quality images by minimizing artifacts induced by limited-angle data and beam hardening.

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Image Reconstruction for Limited-Angle Electron Beam X-Ray Computed Tomography With Energy-Integrating Detectors for Multiphase Flows

The relative motion of the friction and separator plates in wet clutches during the disengaged mode causes viscous shear stresses in the fluid passing through the 100 microns gap. This results in a drag torque on both the disks that wastes energy and decreases fuel economy. The objective of the study is to develop an accurate mathematical model for the above problem with verification using FLUENT and experiments. Initially we start with two flat disks. The mathematical model enables us to calculate the drag torque on the disks and 2D axisymmetric solver verifies the solution. The surface pressure distribution on the plates is also verified. Then 3D models of one grooved and one flat disk are tested using CFD, experiments and an approximated 3D mathematical model and three parameters namely number of grooves, depth of groove and clearance between the disks are studied to understand the effect they have on the drag torque. Conclusions are finally drawn and design implementations are suggested to reduce drag.Copyright © 2004 by ASME

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Modeling and Parametric Study of Torque in Open Clutch Plates

Experiments were performed to examine differences in bubble cavitation inception, form, and acoustic emission in fresh and salt water. The tests were conducted on an axisymmetric headform known as the ITTC body, and acoustic emission, cavitation bubble size, and cavitation event rates were measured for a variety of cavitation numbers and dissolved air contents at a fixed dynamic head for both fresh and salt water. Differences were detected in the cavitation inception index, cavitation bubble size distribution, and the resulting overall acoustic emission. These differences may be attributed to variations in the freestream nuclei population, and it is hypothesized that the solution of salt reduced the number and size offreestream nuclei. Differences in the overall acoustic emission were attributed to variation in the bubble event rate and average maximum bubble size between the fresh and salt water cavitation.

The effects of salt water on bubble cavitation

It is possible, in experimental flows of electrorheological (ER) fluids or in actual ER devices based on shear flows, that the electric field may have a component normal to and/or parallel to the fluid velocity. An analytical study of this possibility is presented here. The analysis is carried out using a constitutive equation for the three‐dimensional response of ER fluids [Rajagopal and Wineman, Acta Mechanica 91 (1992)] in which the electric field influences the response in two ways: (a) by affecting the material parameters, and (b) by contributing to stress components because of the interaction of the electric field vector and the shearing. It is shown that the viscosity is altered by a component of the electric field in the direction of the fluid velocity. Moreover, the viscosity is changed if the shear direction is reversed. The model is used in a study of the flow between parallel plates. It is found that the velocity field need not be symmetric about the midplane and the tractions on the plates may differ.

Steven L. Ceccio

Papers

Perturbed Partial Cavity Drag Reduction at High Reynolds Numbers

Image Reconstruction for Limited-Angle Electron Beam X-Ray Computed Tomography With Energy-Integrating Detectors for Multiphase Flows

Modeling and Parametric Study of Torque in Open Clutch Plates

The effects of salt water on bubble cavitation

Influence of orientation of electric field on shear flow of electrorheological fluids