Implicit Solution of Three-Dimensional Internal Turbulent Flows PDF Download
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722293857
Category :
Languages : en
Pages : 48
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Book Description
The scalar form of the approximate factorization method was used to develop a new code for the solution of three-dimensional internal laminar and turbulent compressible flows. The Navier-Stokes equations in their Reynolds-averaged form are iterated in time until a steady solution is reached. Evidence is given to the implicit and explicit artificial damping schemes that proved to be particularly efficient in speeding up convergence and enhancing the algorithm robustness. A conservative treatment of these terms at domain boundaries is proposed in order to avoid undesired mass and/or momentum artificial fluxes. Turbulence effects are accounted for by the zero-equation Baldwin-Lomax turbulence model and the q-omega two-equation model. For the first, an investigation on the model behavior in case of multiple boundaries is performed. The flow in a developing S-duct is then solved in the laminar regime at Reynolds number (Re) 790 and in the turbulent regime at Re=40,000 using the Baldwin-Lomax model . The Stanitz elbow is then solved using an inviscid version of the same code at M(sub inlet)=0.4. Grid dependence and convergence rate are investigated showing that for this solver the implicit damping scheme may play a critical role for convergence characteristics. The same flow at Re=2.5x10(exp 6) is solved with the Baldwin-Lomax and the q-omega models. Both approaches showed satisfactory agreement with experiments, although the q-omega model is slightly more accurate. Michelassi, V. and Liou, M.-S. and Povinelli, L. A. Glenn Research Center NASA-ORDER C-99066-G; RTOP 505-62-21...
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722293857
Category :
Languages : en
Pages : 48
Get Book Here
Book Description
The scalar form of the approximate factorization method was used to develop a new code for the solution of three-dimensional internal laminar and turbulent compressible flows. The Navier-Stokes equations in their Reynolds-averaged form are iterated in time until a steady solution is reached. Evidence is given to the implicit and explicit artificial damping schemes that proved to be particularly efficient in speeding up convergence and enhancing the algorithm robustness. A conservative treatment of these terms at domain boundaries is proposed in order to avoid undesired mass and/or momentum artificial fluxes. Turbulence effects are accounted for by the zero-equation Baldwin-Lomax turbulence model and the q-omega two-equation model. For the first, an investigation on the model behavior in case of multiple boundaries is performed. The flow in a developing S-duct is then solved in the laminar regime at Reynolds number (Re) 790 and in the turbulent regime at Re=40,000 using the Baldwin-Lomax model . The Stanitz elbow is then solved using an inviscid version of the same code at M(sub inlet)=0.4. Grid dependence and convergence rate are investigated showing that for this solver the implicit damping scheme may play a critical role for convergence characteristics. The same flow at Re=2.5x10(exp 6) is solved with the Baldwin-Lomax and the q-omega models. Both approaches showed satisfactory agreement with experiments, although the q-omega model is slightly more accurate. Michelassi, V. and Liou, M.-S. and Povinelli, L. A. Glenn Research Center NASA-ORDER C-99066-G; RTOP 505-62-21...
Author: V. Michelassi
Publisher:
ISBN:
Category : Turbulence
Languages : en
Pages : 48
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Book Description
Author: Felix J. Pierce
Publisher:
ISBN:
Category : Boundary value problems
Languages : en
Pages : 144
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Book Description
A method of solving the three-dimensional, incompressible turbulent boundary-layer equations was developed using a Crank-Nicholson implicit finite-difference technique, with the turbulent stress terms modeled with an eddy-viscosity model obtained from mixing length theory. The method was applied to two three-dimensional flow geometries for which experimental data exists and a comparison with this data showed excellent agreement. A complete computer program was sufficiently generalized for application to two-dimensional laminar and turbulent flows with arbitrary pressure gradients. The method was applied to several such test cases and the solutions agreed well with both theory and experiment. An analysis was presented to determine the conditions for which the finite difference equations were stable and convergent. (Author).
Author: Michel Deville
Publisher: Springer Science & Business Media
ISBN: 3322898385
Category : Technology & Engineering
Languages : en
Pages : 406
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Book Description
Der Sammelband enthält Beiträge einer Tagung über die Simulation von dreidimensionalen Flüssigkeiten. Sie geben einen Überblick über den Stand des Wissens auf dem Gebiet der numerischen Simulation der Turbulenz, angewandt auf eine weite Spanne von Problemen wie Aerodynamik, Nicht-Newtonsche Flüssigkeiten, Konvektion.This volume contains the material presented at the IMACS-COST Conference on CFD, Three-Dimensional Complex Flows, held in Lausanne (Switzerland), September 13 - 15, 1995. It gives an overview of the current state of numerical simulation and turbulence modelling applied to a wide range of fluid flow problems such as an example aerodynamics, non-Newtonian flows, transition, thermal convection.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 704
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 22
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Author: Kirti N. Ghia
Publisher:
ISBN:
Category :
Languages : en
Pages : 35
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This report describes the technical progress achieved in research sponsored by the Air Force Office of Scientific Research during the period between March 1981 and February 1982. Three areas of research were pursued; two of these consist of analysis of laminar and turbulent duct flows, and study of laminar and turbulent separated flows. Both of these studies were aimed at acquiring a better understanding of isolated physical phenomena significant to turbomachinery applications via the use of appropriate model problems. The third area of research pursued consisted of the analysis of numerical methods with the goal of improving the efficiency and accuracy of the various methods developed and implemented. In the first area of research, fine-grid asymptotic solutions were obtained for laminar flow through curved ducts of simple cross sections; also marching solutions have been obtained for further flow in the entrance region of curved ducts of simple cross sections. The subject of streamwise separation is examined using the laminar flow through a constructed asymmetric channel and the laminar and turbulent flows past a thick blunt plate as the model problems. In the third category, high-Re very fine-grid solutions have been provided for the shear-driven cavity problem using a multi-grid strongly implicit method.
Author: Kirti N. Ghia
Publisher:
ISBN:
Category :
Languages : en
Pages : 43
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This research is motivated by the need for accurate prediction of three-dimensional viscous flow in a turbine or compressor passage. As a major step towards the investigation of these problems, the three-dimensional entrance flow through ducts of various regular cross-sections, with longitudinal and transverse curvature effects, have been studied. The mathematical model has been formulated using time-averaged three-dimensional parabolized Navier-Stokes equations. The analysis has been developed using an existing two-equation turbulence model and is checked by obtaining satisfactory comparison of the present results for straight and curved circular pipes. The effects of the problem parameters on the flow fields are accurately evaluated and the limitations of the turbulence model have been briefly stated. Four related areas were identified and studied separately. These consist of the law of the wall, coordinate transformations and efficiency and accuracy of the numerical algorithm. The last three of these areas have been studied with some success already, and the additional analysis developed will be implemented in the basic turbulent-flow program to make the latter a truly predictive tool.
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ISBN:
Category : Mechanical engineering
Languages : en
Pages : 498
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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