ONE-DIMENSIONAL TWO-PHASE FLOW.

By Prof. Graham B. Wallis{Engineering Sciences). New York: McGraw-Hill Book Company, 1969. 408 pp.$16.50.

With respect for "wind and downy flake" befitting an English-born Vermonter, Graham Wallis has written a very fine text. He has organized the material into Analytical Techniques and Practical Applications, and in so doing he has served both the student seeking a general understanding of the field and the professional seeking information about a particular application.

The author begins by referring to several common examples of two-phase flow, some of which are, "fog, rain, snow, quicksands, ... which occur in nature"; "tea making, cream whipping, spaghetti twirling, coffee percolation, beer pouring, ... frequent occurrences in kitchens"; and fire control, refrigeration, distillation, desalination, and portions of steel making, paper manufacture and food processing, in the industrial field. As implied by the above abbreviated list of examples, one of Wallis' major contributions is to cause such diverse phenomena to yield to a unified analysis. The importance of the subject and unifying nature of the treatment is indicated by the following quote: "Body fluids, such as blood, semen, and milk, are all multiphase, containing a variety of cells, particles, or droplets in a suspension. Their behavior can be described in much the same equations as are used for analyzing paints, inks, pastes, and nuclear fuel slurries."

Although the above examples are rather conversational, it is a serious text. While much of the text is original, particularly the part on analytipal methods, the author draws on 342 references; 1,110 equations, 156 figures, and 41 examples are used to supplement the text. The author's respect for student initiative in learning is indicated in his terse style and the 484 problems supplied.

The treatment of continuity waves was particularly interesting and new to me. It suggested that the major contribution of the text is more than just that a wide range of messy problems, messy in the sense that they don't yield easily to analysis, have been treated. The major contribution, it seems to me, is that in doing this, Professor Wallis has allowed engineering education to efficiently treat a field that has been largely omitted, not because of any lack of importance, but because it was difficult to treat. This should help offset the present overemphasis on mathematical analogies. I hope that his present success will encourage the author to publish a similar treatment of transport phenomena in two-phase flow.

Mr. Converse is Associate Professor of Engineering at Thayer School.