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Shear flow
About: Shear flow is a research topic. Over the lifetime, 17591 publications have been published within this topic receiving 524031 citations.
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TL;DR: In this paper, a complete set of perturbations, ordered by energy growth, is found using variational methods. But the optimal perturbation is not of modal form, and those which grow the most resemble streamwise vortices, which divert the mean flow energy into streaks of streamwise velocity and enable the energy of the perturbance to grow by as much as three orders of magnitude.
Abstract: Transition to turbulence in plane channel flow occurs even for conditions under which modes of the linearized dynamical system associated with the flow are stable. In this paper an attempt is made to understand this phenomena by finding the linear three‐dimensional perturbations that gain the most energy in a given time period. A complete set of perturbations, ordered by energy growth, is found using variational methods. The optimal perturbations are not of modal form, and those which grow the most resemble streamwise vortices, which divert the mean flow energy into streaks of streamwise velocity and enable the energy of the perturbation to grow by as much as three orders of magnitude. It is suggested that excitation of these perturbations facilitates transition from laminar to turbulent flow. The variational method used to find the optimal perturbations in a shear flow also allows construction of tight bounds on growth rate and determination of regions of absolute stability in which no perturbation growth is possible.
1,083 citations
Book•
30 Aug 1990
TL;DR: In this article, the authors present a reference record created on 2005-11-18, modified on 2016-08-08, using the term "fluid reference record" to describe the fluides reference record.
Abstract: Keywords: ecoulement : turbulent ; mecanique des : fluides ; statistique ; simulation ; structures ; turbulence ; fluides Reference Record created on 2005-11-18, modified on 2016-08-08
1,056 citations
TL;DR: The Structure of Turbulent Shear Flow by Dr. A.Townsend as mentioned in this paper is a well-known work in the field of fluid dynamics and has been used extensively in many applications.
Abstract: The Structure of Turbulent Shear Flow By Dr. A. A. Townsend. Pp. xii + 315. 8¾ in. × 5½ in. (Cambridge: At the University Press.) 40s.
1,050 citations
TL;DR: In this paper, the authors provided a model of turbulence which effects closure through approximated transport equations for the Reynolds stress tensor the turbulence energy κ and e.g., the turbulent shear stress does not vanish where the mean rate of strain goes to zero.
Abstract: The paper provides a model of turbulence which effects closure through approximated transport equations for the Reynolds stress tensor the turbulence energy κ and e. This model has been incorporated in the numerical solution procedure of Patankar & Spalding (1970) and applied to the prediction of a number of boundary-layer flows including examples of flow remote from walls, those developing along one wall and those confined within ducts. Three of the flows are strongly asymmetric with respect to the surface of zero shear stress and here the turbulent shear stress does not vanish where the mean rate of strain goes to zero. In most cases the predicted profiles and other quantities accord with the data within the probable accuracy of the measurements.
1,026 citations