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Prediction methods for turbulent flows
Computers & Oeosciences Vet. 8, No. 2, pp. 231-232, 1982 Printed in Great Britain.
0098-3004182/020231-02503.00/0 Pergamon Press Ltd.
BOOK REVIEWS An alternative method for predicting a turbulent flow is to use a direct numerical simulation of the turbulence or a large-eddy simulation. These methods solve for the This book is a collection of the notes of a lecture series energy containing eddies explicitly. For high Reynolds on Prediction Methods for Turbulent Flows held 15-19 number flows, some assumption is needed about the January 1979, by the yon Karman Institute. There is a motions smaller than the grid size (sub-grid scale modelneed to be able to predict the turbulent flow in the ling). The current status of these methods is well covered environment in a number of situations. Of the 7 papers, in the section by Schumann, Grttzbach, and Kleiser. the most relevant and useful as far as practical methods Such models have been used with great success in for predicting geophysical flows are concerned is that by modelling two-dimensional turbulence, which is relevant Rodi. He discusses the turbulence closure techniques to the synoptic-scale motions in the atmosphere and currently used. The presentation is neat and concise, ocean. With the computing speed of present day comdescribing the hierarchy of closure models from simple puters, it has become feasible to model fully threemixing-length theory to so called "second-order" closure dimensional turbulence albeit on a rather restricted grid models in which transport equations are written for the size and for idealized flows. The results are encouraging individual Reynolds stress terms. He gives many exam- but the major use of such models will be in testing and ples of the application of such models, the most widely improving turbulence closure models. The section by Nihoul is on turbulence in the ocean. used being the k-e model where the turbulent kinetic energy and dissipation are determined from transport He opens with a discussion on the linear waves occurring equations and the Reynolds stresses related to the local at many length-scales in the ocean. Using a scale analysis, he indicates on a frequency-wave number diagram velocity gradient. The k-e model has been tested for a wide range of the domains in which there is both a response flows of environmental interest with the results showing mechanism to external forcing and strong non-linear a certain amount of success. Rodi favours the use of interactions turning the associated motion into tursuch a model, arguing that there is no advantage at bulence. These regions cover synoptic eddies to Kelvinpresent in using a more complicated one. In most of Helmholtz billow turbulence but he gives no practical the applications, the same empirical constants have been method for their prediction. The last two papers by Jones and Borghi are on used to give reasonable agreement with experiment. The exception is the spreading rates of jets into a surrounding combustion in a turbulent field. Such flows have their flow where different values of the constants are needed own special problems with large density variations and to fit the data for different kinds of jet. Without a the combustion rate being dependent on the instantaneous universality of such constants, any turbulence model values of the concentration of the reactants. The book offers a good coverage of the state of the art ceases to be predictive and becomes little more than a curve-fitting routine. The more complicated the model of prediction methods for turbulent flows. A number of the more constants the user has at his disposal. Despite the methods discussed are still in their infancy and are this, a number of authors still tune their models to fit not applicable directly to geophysical problems. From a practical point of view, however, there are models which their results. Lumley describes second-order closure modelling in do give a reasonable prediction of some environmental more detail. He gives his own preference for the many flows. The reader is cautioned into using these models assumptions that are needed to close such a system but with care and in situations in which they have been well gives no indication of the importance of these assump- tried and tested. tions for a particular flow or when simpler models are K. J. POCttARDS Institute of Oceanographic appropriate. Sciences Turbulence closure methods have been discovered to Wormley, Godalming give poor results in a number of flow situations. Mathieu Surrey and Jeandel consider a number of "pathological cases" England or idealized flow situations, such as isotropic turbulence undergoing a succession of plane strains. They show the inadequacies of predictive methods based on closure Elementary Nmaerkal AmdyJis, by S. D. Conte and C. de methods for these situations and suggest that this is Boor. McGraw-Hill, New York, 1980, 432 p. £6.50. because there are several characteristic scales in the flow. They suggest that these difficulties can be over- This is the third edition of a volume in the McGraw-Hill come by using spectral methods, although this is not a new International Student Editions. Its small paperback format is packed with information. It encompasses the idea. Predietian Methods for Turbulent Flows, edited by Wolfgang Kollman. McGraw-Hill (Hemisphere), 1981. £25.25.
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0098-3004182/020231-02503.00/0 Pergamon Press Ltd.
BOOK REVIEWS An alternative method for predicting a turbulent flow is to use a direct numerical simulation of the turbulence or a large-eddy simulation. These methods solve for the This book is a collection of the notes of a lecture series energy containing eddies explicitly. For high Reynolds on Prediction Methods for Turbulent Flows held 15-19 number flows, some assumption is needed about the January 1979, by the yon Karman Institute. There is a motions smaller than the grid size (sub-grid scale modelneed to be able to predict the turbulent flow in the ling). The current status of these methods is well covered environment in a number of situations. Of the 7 papers, in the section by Schumann, Grttzbach, and Kleiser. the most relevant and useful as far as practical methods Such models have been used with great success in for predicting geophysical flows are concerned is that by modelling two-dimensional turbulence, which is relevant Rodi. He discusses the turbulence closure techniques to the synoptic-scale motions in the atmosphere and currently used. The presentation is neat and concise, ocean. With the computing speed of present day comdescribing the hierarchy of closure models from simple puters, it has become feasible to model fully threemixing-length theory to so called "second-order" closure dimensional turbulence albeit on a rather restricted grid models in which transport equations are written for the size and for idealized flows. The results are encouraging individual Reynolds stress terms. He gives many exam- but the major use of such models will be in testing and ples of the application of such models, the most widely improving turbulence closure models. The section by Nihoul is on turbulence in the ocean. used being the k-e model where the turbulent kinetic energy and dissipation are determined from transport He opens with a discussion on the linear waves occurring equations and the Reynolds stresses related to the local at many length-scales in the ocean. Using a scale analysis, he indicates on a frequency-wave number diagram velocity gradient. The k-e model has been tested for a wide range of the domains in which there is both a response flows of environmental interest with the results showing mechanism to external forcing and strong non-linear a certain amount of success. Rodi favours the use of interactions turning the associated motion into tursuch a model, arguing that there is no advantage at bulence. These regions cover synoptic eddies to Kelvinpresent in using a more complicated one. In most of Helmholtz billow turbulence but he gives no practical the applications, the same empirical constants have been method for their prediction. The last two papers by Jones and Borghi are on used to give reasonable agreement with experiment. The exception is the spreading rates of jets into a surrounding combustion in a turbulent field. Such flows have their flow where different values of the constants are needed own special problems with large density variations and to fit the data for different kinds of jet. Without a the combustion rate being dependent on the instantaneous universality of such constants, any turbulence model values of the concentration of the reactants. The book offers a good coverage of the state of the art ceases to be predictive and becomes little more than a curve-fitting routine. The more complicated the model of prediction methods for turbulent flows. A number of the more constants the user has at his disposal. Despite the methods discussed are still in their infancy and are this, a number of authors still tune their models to fit not applicable directly to geophysical problems. From a practical point of view, however, there are models which their results. Lumley describes second-order closure modelling in do give a reasonable prediction of some environmental more detail. He gives his own preference for the many flows. The reader is cautioned into using these models assumptions that are needed to close such a system but with care and in situations in which they have been well gives no indication of the importance of these assump- tried and tested. tions for a particular flow or when simpler models are K. J. POCttARDS Institute of Oceanographic appropriate. Sciences Turbulence closure methods have been discovered to Wormley, Godalming give poor results in a number of flow situations. Mathieu Surrey and Jeandel consider a number of "pathological cases" England or idealized flow situations, such as isotropic turbulence undergoing a succession of plane strains. They show the inadequacies of predictive methods based on closure Elementary Nmaerkal AmdyJis, by S. D. Conte and C. de methods for these situations and suggest that this is Boor. McGraw-Hill, New York, 1980, 432 p. £6.50. because there are several characteristic scales in the flow. They suggest that these difficulties can be over- This is the third edition of a volume in the McGraw-Hill come by using spectral methods, although this is not a new International Student Editions. Its small paperback format is packed with information. It encompasses the idea. Predietian Methods for Turbulent Flows, edited by Wolfgang Kollman. McGraw-Hill (Hemisphere), 1981. £25.25.
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