P. Comte – författare

Large-Eddy Simulations of Turbulence is an ideal introduction for people new to LES [large-eddy simulation], direct numerical simulation and Reynolds-averaged Navier-Stokes simulation, and as a reference for researchers. Of particular interest in the text are the detailed discussion, in Chapter 2, of vorticity, pressure, and the velocity gradient tensor, quantities useful for probing the results of a simulation, particularly when looking for coherent vortices and coherent structures. Chapters 4 and 5 feature an in-depth discussion of spectral subgrid-scale modeling. Although physical-space models are generally more readily applied, spectral models give insight into the requirements and limitations in subgrid-scale modeling and backscattering. A third special feature is the detailed discussion in Chapter 7, of large-eddy simulation of compressible flows previously only available in articles scattered throughout the literature. This will be of interest to those dealing with supersonic flows, combustion, astrophysics, and other related topics.

This volume contains papers arising out of the program of the Institute for Theoretical Physics (ITP) of the University of California at Santa Bar­ bara, August-December 1991, on the subject "Topological Fluid Dynamics". The first group of papers cover the lectures on Knot Theory, Relaxation un­ der Topological Constraints, Kinematics of Stretching, and Fast Dynamo Theory presented at the initial Pedagogical Workshop of the program. The remaining papers were presented at the subsequent NATO Advanced Re­ search Workshop or were written during the course of the program. We wish to acknowledge the support of the NATO Science Committee in making this workshop possible. The scope of "Topological Fluid Dynamics" was defined by an earlier Symposium of the International Union of Theoretical and Applied Mechan­ ics (IUTAM) held in Cambridge, England in August, 1989, the Proceedings of which were published (Eds. H.K. Moffatt and A. Tsinober) by Cambridge University Press in 1990. The proposal to hold an ITP program on this sub­ ject emerged from that Symposium, and we are grateful to John Greene and Charlie Kennel at whose encouragement the original proposal was formu­ lated. Topological fluid dynamics covers a range of problems, particularly those involving vortex tubes and/or magnetic flux tubes in nearly ideal fluids, for which topological structures can be identified and to some extent quantified.

The intimate relationship between three-dimensional vortex dynamics and topology was recognized as early as 1869 by Lord Kelvin, whose discoveries in fluid dynamics led to the development of knot theory as a well-defined branch of topology. It is only in the last 25 years, however, with the parallel stimulus of the development of magnetohydrodynamics in astrophysical and geophysical contexts, that the great potential of topological techniques in fluid and plasma has been fully recognized. This volume provides a comprehensive survey of this interdisciplinary field. The relevant background in knot theory, flow kinematics, dynamo theory, and relaxation under topological constraints, is provided by the introductory chapters of Part I. These themes are developed in the subsequent papers which are grouped under the following headings: Part II: Relaxation and Minimum Energy States; Part III: Helicity, Linkage, and Flow Topology; Part IV: The Euler Equations: Extremal Properties and Finite-Time Singularities; Part V: Vortex Interactions and the Structure of Turbulence; Part VI: Chaos, Instability, and Dynamo Theory.