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Annual review of fluid mechanics
ICARUS 24, 139--141 (1975)
Book R e v i e w s Annual Review of Fluid Mechanics. Edited by Milton Van Dyke and Walter G. Vincenti, Vol. 6. Annual Reviews, Palo Alto, California 1974. 371 pp. Price $15.00.
confidence in theory is now rare in fluid mechanics, although it m ay be justified for this linear problem. "Double-Diffusive P h e n o m e n a " by J . S. Turner refers to buoyancy-driven flows in which Fluid mechanics is an exasperating subject there are two components (e.g., heat and salt) for m a n y in the field of solar system studies. making opposite contributions to the density Neither theory nor experiment seems capable distribution. Density differences are produced of accounting for the behavior of a single cumby the different diffusion rates of the two ulus cloud, much less t h a t of an entire planetary components. Turner briefly discusses the linear atmosphere. Yet fluid mechanics is an estabstability analysis, in which gradients are weak lished, sophisticated discipline requiring m a n y and a tractable theoretical problem can be years to master. The average planetary observer formulated. However, when the gradients are has better things to do with his professional time increased in a laboratory experiment, phenomena than to learn fluid mechanics, y e t much of what occur which are presently outside the range of he observes can only be understood in terms of theory. Well-mixed layers, separated by interfluid dynamical models. Observers who enter faces across which there are large gradients, into arguments of a fluid dynamical nature tend to form in the interior of the fluid. Such should either be humble or else learn dynamics, vertical layering has been observed in the oceans, just as specialists in dynamics should be humble and m ay occur in other natural settings. in presenting simplified models of natural O. M. Phillips, in his article "Nonlinear phenomena. Dispersive W av es," discusses how a finite number of weakly coupled wave modes can slowly The Annual Review of JFluid Mechanics c a n help to resolve some of these difficulties. exchange energy and momentum. The case of I t gives the nonspecialist a feel for current continuous wave spectra, which m a y be the research in fluid mechanics: what problems are most relevant in a real ocean or atmosphere, is of interest, how they are approached, and what not treated. Hans A. Panofsky, in his article one can expect of the result. And i t gives the "The Atmospheric Boundary Layer Below specialist new ideas, new techniques and new 150 Meters," presents data relating mean results to apply to his own problems of interest. profiles of heat, momentum, moisture, etc., %o Thus Volume 6 of this series might be of some the spectra and vertical fluxes of these quantities. interest to a number of I c a r ~ readers and of Scaling arguments provide the theoretical great interest to a few. framework for presenting the large body of This volume consists of 13 articles, seven of observational material. which will be discussed here because of their "Spin-Up," by E. R. Benton and A. Clark, Jr., greater interest to Icarus readers. " T h e Interdescribes theory and experiment on the adjustaction Between E x p e r i m e n t and Theory in ment of a fluid to a change in angular velocity Fluid Mechanics" by G. I. Taylor describes of its container. Unfortunately, except in a few Taylor's approach to fluid mechanics in which instances, the experiments have not gone m u c h simple laboratory experiments are used to beyond the range of validity of the theory. Thus extend the range of basic theoretical concepts, in most of the potential applications, involving t h e order to develop a qualitative understanding. interiors of planets and stars, are still outside the Included is a description of Taylor's classic work range of either theory or experiment. This on rotating fluids. I n contrast, J o h n W. Miles includes the question of solar spin-down, which takes a more engineering approach in his chapter is discussed at some length in this chapter. on " H a r b o r Seiching." H e reviews the theory Finally, Steven A. Orszag and Moshe Israeli of small-amplitude oscillations, both forced and present a chapter on "Numerical Simulation of free, of harbors of various dimensions. The analyViscous Incompressible Flows." Their philosophy sis is linear, and Miles feels t h a t numerical is t h a t numerical simulations are useful to give calculations will soon be as reliable, and much physical insight, b u t not primarily to generate cheaper than, model tests in predicting the main "realistic" flows or to develop numerical techfeatures of seiching in a particular harbor. Such niques. They discuss the relative merits of Copyright O 1975 by Academic Press, Inc. 139 All rights of reproduction in any form reserved. Printed in Great Britain
140
BOOK REVIEWS
second-vs, higher-order schemes for expressing derivatives in finite-difference form, and compare these methods with spectral methods, which generally require less computer m e m o r y and computer time for comparable accuracy. This chapter will be useful to someone who is interested in numerical modeling.
Martin, City University, London, E.C.1) and we wish them a long and successful life. CARL SAG~'~
Laboratory for Planetary Studies Cornell University Ithaca, New York 14850
AXDREW P. I~G~a~SOLL
Division of Geological and Planetary Sciences California Institute of Technology Pasadena, California 91109
Journal of the British Interplanetary Society (Bed cover Interstellar issue). Edited by A. R. MA~TI~. Volume 27, number 4, April 1974. British Interplanetary Society, London. 80 pp. Price $33 per year. In the 1930's, when the mere idea of interplanetary flight was considered the rankest speculation in the minds ofa!l but a few dreamers, the British Interplanetary Society was undertaking a serious engineering study of a manned lunar mission. Thirty years later, such a mission was accomplished. The Apollo design configuration did not closely resemble t h a t of the BIS, but the BIS lunar mission configuration played a historically important role, that of the existence theorem. At the present time the British Interplanetary Society is working on a much more ambitious detailed engineering design---of an unmanned interstellar mission, perhaps to Barnard's star. I t may again take 30 yr from first study to launch, but the historical significance of this study may be even greater. The detailed engineering design is apparently at least a year away. Meanwhile the Society has begun, with its April 1974 issue (Vol. 27, No. 4), a series of red covered issues of its Journal devoted to the engineering and scientific aspects of interstellar communication. The emphasis is on space vehicles, but not exclusively. F o r example, there is an interesting paper by A. T. Lawton which attempts a comparison of the utility of unmanned intelligent machine probes and interstellar radio communication. Other papers are on the exhaust velocity, flight time, and trajectory optimization of interstellar flight ; a discussion of conceivable liquid ammonia biochemistries, which, remarkably, mentions the work of neither ttenderson nor t t al d an e; and extensive reviews of recent relev a n t papers and books. These interstellar studies issues of the J B I S have a separate editor (A. R.
Communication with Extraterrestrial Intelligence (CETI). Edited by Carl Sagan. MIT Press, Cambridge, Mass., 1973. 428-[-xxxvi pp. Price $10.00. " C E T I is an idea whose time has come." I forget who said t h a t - - p r o b a b l y Carl Sagan, editor of this Conference proceedings. After reading this book, I am inclined to agree. W h a t is CETI? Communication with E x t r a Terrestrial Intelligence, yes, but also the genetive of eetus, whale, reminding us of both the intriguingly intelligent but still remote Cetacean species on earth ; and also of Tau Ceti, a nearby star listened to first in 1960 by F r an k Drake as part of Project Ozma at N R A O and more recently at Gorky in 1971 and again at N R A O in 1973, all without success. More than that, C E T I is the dream of a widespread band of scientists and engineers, a sample of whom were invited to a 1971 conference in Yerevan, the capital of Soviet Armenia, to discuss the prospects. The conference was co-sponsored by the National Academy of Sciences and the Soviet Academy of Sciences. The present volume is derived from the transcript of the proceedings. First, the players. Carl Sagan, F r an k Drake, and Philip Morrison are well known as leaders of the movement. Then, m a n y talented people, like Dyson, Hubel, Minsky, Oliver, Townes, and Crick from the West, together with a similar Soviet t e a m including Ambartsumian, Kardasher, Shklovsky, Ginzburg, Kaplan, and Moroz. A sprinkling of historians, linguists, and anthropologists completed the group. The game centered on Drake's equation, N= R . f p nefif~fc L, for the number of civilizations in the Galaxy able to communicate across interstellar distances. The factors refer to the rate of birth of such civilizations (via origin of stars, planets, life, intelligence and communication technique) and the length of time (L) which they are expected to last. At one extreme, McNeill argued (p. 116) t h a t the Drake equation is meaningless, because it arbitrarily assigns probabilities to some five steps recognized as being critical. I f more careful analyses had yielded a hundred steps, he argued, then less-
Book R e v i e w s Annual Review of Fluid Mechanics. Edited by Milton Van Dyke and Walter G. Vincenti, Vol. 6. Annual Reviews, Palo Alto, California 1974. 371 pp. Price $15.00.
confidence in theory is now rare in fluid mechanics, although it m ay be justified for this linear problem. "Double-Diffusive P h e n o m e n a " by J . S. Turner refers to buoyancy-driven flows in which Fluid mechanics is an exasperating subject there are two components (e.g., heat and salt) for m a n y in the field of solar system studies. making opposite contributions to the density Neither theory nor experiment seems capable distribution. Density differences are produced of accounting for the behavior of a single cumby the different diffusion rates of the two ulus cloud, much less t h a t of an entire planetary components. Turner briefly discusses the linear atmosphere. Yet fluid mechanics is an estabstability analysis, in which gradients are weak lished, sophisticated discipline requiring m a n y and a tractable theoretical problem can be years to master. The average planetary observer formulated. However, when the gradients are has better things to do with his professional time increased in a laboratory experiment, phenomena than to learn fluid mechanics, y e t much of what occur which are presently outside the range of he observes can only be understood in terms of theory. Well-mixed layers, separated by interfluid dynamical models. Observers who enter faces across which there are large gradients, into arguments of a fluid dynamical nature tend to form in the interior of the fluid. Such should either be humble or else learn dynamics, vertical layering has been observed in the oceans, just as specialists in dynamics should be humble and m ay occur in other natural settings. in presenting simplified models of natural O. M. Phillips, in his article "Nonlinear phenomena. Dispersive W av es," discusses how a finite number of weakly coupled wave modes can slowly The Annual Review of JFluid Mechanics c a n help to resolve some of these difficulties. exchange energy and momentum. The case of I t gives the nonspecialist a feel for current continuous wave spectra, which m a y be the research in fluid mechanics: what problems are most relevant in a real ocean or atmosphere, is of interest, how they are approached, and what not treated. Hans A. Panofsky, in his article one can expect of the result. And i t gives the "The Atmospheric Boundary Layer Below specialist new ideas, new techniques and new 150 Meters," presents data relating mean results to apply to his own problems of interest. profiles of heat, momentum, moisture, etc., %o Thus Volume 6 of this series might be of some the spectra and vertical fluxes of these quantities. interest to a number of I c a r ~ readers and of Scaling arguments provide the theoretical great interest to a few. framework for presenting the large body of This volume consists of 13 articles, seven of observational material. which will be discussed here because of their "Spin-Up," by E. R. Benton and A. Clark, Jr., greater interest to Icarus readers. " T h e Interdescribes theory and experiment on the adjustaction Between E x p e r i m e n t and Theory in ment of a fluid to a change in angular velocity Fluid Mechanics" by G. I. Taylor describes of its container. Unfortunately, except in a few Taylor's approach to fluid mechanics in which instances, the experiments have not gone m u c h simple laboratory experiments are used to beyond the range of validity of the theory. Thus extend the range of basic theoretical concepts, in most of the potential applications, involving t h e order to develop a qualitative understanding. interiors of planets and stars, are still outside the Included is a description of Taylor's classic work range of either theory or experiment. This on rotating fluids. I n contrast, J o h n W. Miles includes the question of solar spin-down, which takes a more engineering approach in his chapter is discussed at some length in this chapter. on " H a r b o r Seiching." H e reviews the theory Finally, Steven A. Orszag and Moshe Israeli of small-amplitude oscillations, both forced and present a chapter on "Numerical Simulation of free, of harbors of various dimensions. The analyViscous Incompressible Flows." Their philosophy sis is linear, and Miles feels t h a t numerical is t h a t numerical simulations are useful to give calculations will soon be as reliable, and much physical insight, b u t not primarily to generate cheaper than, model tests in predicting the main "realistic" flows or to develop numerical techfeatures of seiching in a particular harbor. Such niques. They discuss the relative merits of Copyright O 1975 by Academic Press, Inc. 139 All rights of reproduction in any form reserved. Printed in Great Britain
140
BOOK REVIEWS
second-vs, higher-order schemes for expressing derivatives in finite-difference form, and compare these methods with spectral methods, which generally require less computer m e m o r y and computer time for comparable accuracy. This chapter will be useful to someone who is interested in numerical modeling.
Martin, City University, London, E.C.1) and we wish them a long and successful life. CARL SAG~'~
Laboratory for Planetary Studies Cornell University Ithaca, New York 14850
AXDREW P. I~G~a~SOLL
Division of Geological and Planetary Sciences California Institute of Technology Pasadena, California 91109
Journal of the British Interplanetary Society (Bed cover Interstellar issue). Edited by A. R. MA~TI~. Volume 27, number 4, April 1974. British Interplanetary Society, London. 80 pp. Price $33 per year. In the 1930's, when the mere idea of interplanetary flight was considered the rankest speculation in the minds ofa!l but a few dreamers, the British Interplanetary Society was undertaking a serious engineering study of a manned lunar mission. Thirty years later, such a mission was accomplished. The Apollo design configuration did not closely resemble t h a t of the BIS, but the BIS lunar mission configuration played a historically important role, that of the existence theorem. At the present time the British Interplanetary Society is working on a much more ambitious detailed engineering design---of an unmanned interstellar mission, perhaps to Barnard's star. I t may again take 30 yr from first study to launch, but the historical significance of this study may be even greater. The detailed engineering design is apparently at least a year away. Meanwhile the Society has begun, with its April 1974 issue (Vol. 27, No. 4), a series of red covered issues of its Journal devoted to the engineering and scientific aspects of interstellar communication. The emphasis is on space vehicles, but not exclusively. F o r example, there is an interesting paper by A. T. Lawton which attempts a comparison of the utility of unmanned intelligent machine probes and interstellar radio communication. Other papers are on the exhaust velocity, flight time, and trajectory optimization of interstellar flight ; a discussion of conceivable liquid ammonia biochemistries, which, remarkably, mentions the work of neither ttenderson nor t t al d an e; and extensive reviews of recent relev a n t papers and books. These interstellar studies issues of the J B I S have a separate editor (A. R.
Communication with Extraterrestrial Intelligence (CETI). Edited by Carl Sagan. MIT Press, Cambridge, Mass., 1973. 428-[-xxxvi pp. Price $10.00. " C E T I is an idea whose time has come." I forget who said t h a t - - p r o b a b l y Carl Sagan, editor of this Conference proceedings. After reading this book, I am inclined to agree. W h a t is CETI? Communication with E x t r a Terrestrial Intelligence, yes, but also the genetive of eetus, whale, reminding us of both the intriguingly intelligent but still remote Cetacean species on earth ; and also of Tau Ceti, a nearby star listened to first in 1960 by F r an k Drake as part of Project Ozma at N R A O and more recently at Gorky in 1971 and again at N R A O in 1973, all without success. More than that, C E T I is the dream of a widespread band of scientists and engineers, a sample of whom were invited to a 1971 conference in Yerevan, the capital of Soviet Armenia, to discuss the prospects. The conference was co-sponsored by the National Academy of Sciences and the Soviet Academy of Sciences. The present volume is derived from the transcript of the proceedings. First, the players. Carl Sagan, F r an k Drake, and Philip Morrison are well known as leaders of the movement. Then, m a n y talented people, like Dyson, Hubel, Minsky, Oliver, Townes, and Crick from the West, together with a similar Soviet t e a m including Ambartsumian, Kardasher, Shklovsky, Ginzburg, Kaplan, and Moroz. A sprinkling of historians, linguists, and anthropologists completed the group. The game centered on Drake's equation, N= R . f p nefif~fc L, for the number of civilizations in the Galaxy able to communicate across interstellar distances. The factors refer to the rate of birth of such civilizations (via origin of stars, planets, life, intelligence and communication technique) and the length of time (L) which they are expected to last. At one extreme, McNeill argued (p. 116) t h a t the Drake equation is meaningless, because it arbitrarily assigns probabilities to some five steps recognized as being critical. I f more careful analyses had yielded a hundred steps, he argued, then less-