7R46. Schlieren and Shadowgraph Techniques: Visualizing Phenomena in Transport Media. - GS Settles (Gas Dyn Lab, Penn State Univ, 301 D Reber Bldg, Univ Park PA 16802). Springer-Verlag, Berlin. 2001. 376 pp. ISBN 3-540-66155-7. $89.95.

Reviewed by EE Covert (Dept of Aeronaut and Astronaut, MIT, 77 Massachusetts Ave, Rm 9-466, Cambridge MA 02139-4307).

The title defines the contents of this book. It is printed in a small type (8 point), and is 376 pages long, including seven pages of colored plates at the end of the book. It also contains 1020 cited references. To quote from the Preface, “No attempt was made to cite all of the thousands of literature references in which the subject techniques are mentioned or used.” Yet this reviewer believes Professor Settles has done an outstanding job of culling pertinent material from this richness.

The chapter titles of the book are Historical Background, Basic Concepts, Toepler’s Schlieren Technique, Large Field and Focusing Methods, Specialized Schlieren Techniques, Shadowgraph Techniques, Practical Issues, Setting Up Your Own Simple Schlieren and Shadowgraph System, Applications, Qualitative Evaluation, Summary and Outlook. In addition, there are three Appendices: A–Optical Fundamentals, B–The Schlieren System as a Fourier Optical Processor, and C–Suppliers of Schlieren Systems and Components.

This reviewer believes that the author has met or exceeded his goal to “…fulfill the needs of the novice for basic information, as well as those of the professional for a thorough treatment of the topic.” To his credit, Settles goes to great lengths to define the origin of the term “Schlieren” and to separate Schlieren and Shadowgraph systems from other optical techniques including Kirilian photography. The historical chapter is very interesting. Who, among most of us, knew that Hooke was the father of Schlieren Systems?

As a former supersonic wind tunnel operator, this reviewer found Chapters 2 and 3 to be of top quality, indeed as are Chapters 7 and 8. Settles has written an excellent discussion of Sensitivity, Range, and Resolving Power in Chapter 3. But, he also notes that experience is an important factor in interpreting the images. The author is clearly of a practical mind recommending the use of low cost high intensity automobile headlight bulbs as light sources, and steering the new practitioner away from high cost laser light systems. However, he admits that lasers are a useful light source if the proper cutoff is used. The careful reader will find useful bits of information in each chapter.

Like many experts, Settles cannot resist offering his view of the future of Schlieren systems and their application. In particular, he feels multipath and high-sensitivity Schlieren and resonant refractivity are “…ill explored pathways…” He also sees growth in the use of Schlieren microscopy, both in normal and in stereo, as well as the use of Schlieren procedures as a quality control tool for transparent film and plate manufacture and for imaging for acoustics and heating and ventilating. This reviewer feels that a quantitative Schlieren is an admirable goal, but for so-called “two-dimensional flows,” which are really three-dimensional approximations to a plane flow, the mathematical difficulties in tracing back the elementary contributions from the path integral are demanding, unless a very sharp focusing Schlieren system is available. In the case of axially symmetric flow, the mathematical tools are available, but involve solving an Abelian integral equation with its singular kernel.

The book has very few detectable typographical errors. The most obvious is line 12, page 286. Occasionally, the typist hits the space bar in the middle of a word, which is only an annoyance. The index is quite complete, but a space between each change in the letters of the alphabet would have been appreciated.

This reviewer recommends Schlieren and Shadowgraph Techniques: Visualizing Phenomena in Transport Media to anyone interested in optical systems for flow visualization, and other studies benefiting from visualization of physical phenomena of transparent media. Even in the current period of competition for resources, an engineering librarian should carefully consider the customer’s needs before deciding not to add this book to the library’s collection.