Impact of Turbulence Modeling on Numerical Accuracy and Efficiency of Compressible Flow Simulations PDF Download

Author: Thomas J. Coakley
Publisher:
ISBN:
Category :
Languages : en
Pages : 14

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Author: Tuncer Cebeci
Publisher: Springer Science & Business Media
ISBN: 9783540402886
Category : Science
Languages : en
Pages : 140

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Book Description
After a brief review of the more popular turbulence models, the author presents and discusses accurate and efficient numerical methods for solving the boundary-layer equations with turbulence models based on algebraic formulas (mixing length, eddy viscosity) or partial-differential transport equations. A computer program employing the Cebeci-Smith model and the k-e model for obtaining the solution of two-dimensional incompressible turbulent flows without separation is discussed in detail and is presented in the accompanying CD.

Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 542

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Author: Alain Dervieux
Publisher: Springer Science & Business Media
ISBN:
Category : Mathematics
Languages : en
Pages : 604

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Book Description
This volume contains contributions to the BRITE-EURAM 3rd Framework Programme ETMA and extended articles of the TMA-Workshop. It focusses on turbulence modelling techniques suitable to use in typical flow configurations, with emphasis on compressibility effects and inherent unsteadiness. These methodologies are applied to the Navier-Stokes equations, involving various turbulence modelling levels from algebraic to RSM. Basic turbulent flows in aeronautics are considered; mixing layers, wall-flows (flat-plate, backward-facing step, ramp, bump), and more complex configurations (bump, aerofoil). A critical assessment of the turbulence modelling performances is offered, based on previous results and on the experimental data-base of this research programme. The ETMA results figure in the data-base constituted by all partners and organized by INRIA

Author: Konstantin Volkov
Publisher: BoD – Books on Demand
ISBN: 9535133497
Category : Science
Languages : en
Pages : 252

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Book Description
Accurate prediction of turbulent flows remains a challenging task despite considerable work in this area and the acceptance of CFD as a design tool. The quality of the CFD calculations of the flows in engineering applications strongly depends on the proper prediction of turbulence phenomena. Investigations of flow instability, heat transfer, skin friction, secondary flows, flow separation, and reattachment effects demand a reliable modelling and simulation of the turbulence, reliable methods, accurate programming, and robust working practices. The current scientific status of simulation of turbulent flows as well as some advances in computational techniques and practical applications of turbulence research is reviewed and considered in the book.

Author: Alejandra Uranga
Publisher:
ISBN:
Category : Fluid mechanics
Languages : en
Pages : 334

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Book Description
A numerical analysis of the flow over stationary and transversely oscillating circular cylinders at Reynolds numbers of 3900 and 3600, respectively, is undertaken to assess various turbulence modeling techniques for the simulation of vortex shedding phe-nomena. Four turbulence models are considered; namely the one-equation Spalart-Allmaras model [Spalart & Allmaras (1994)] and the k-T model by Speziale et al. (1992) for URANS closure, the constant-coefficient Smagorinsky-Lilly- subgrid-scale model for Large Eddy Simulations, and the adaptive k-T, model proposed by Magag?nato Gabi (2002) for Very Large Eddy Simulations. A key contribution of this work is comparison of results obtained with the same numerical procedure, discretization algorithms, and artificial dissipation but different turbulence modeling techniques in order to properly differentiate between errors due to numerical and to modeling aspects. Through the study of the flow around the stationary cylinder, it is shown that the use of an inadequate time step has a small effect on global average quantities, but a noticeable impact on the pressure coefficient around the cylinder, as well as on the evolution of velocity along the centerline, thus showing that simulations with too large a time step are unable to properly resolve the recirculation zone and wake. Global average quantities are found to be relatively insensitive to three-dimensional resolution. Detailed analysis of three-dimensional URANS simulations reveals that the Spalart-Allmaras model is unable to properly predict the location of the separation point. separation being delayed significantly. This results in too small a mean recircula?tion zone, under-estimated back-pressure. and up to 25% over-estimation of the drag. Yet, this simple model provides an accurate value for the Strouhal number and good fluctuating velocity profiles. The k-T Speziale turbulence model predicts all global quantities accurately, and yields good velocity profiles along the wake as well as an adequate pressure distribution on the cylinder wall. Large and Very Large Eddy Simulations of the flow around a stationary cylinder reveal an important three-dimensionality, and the formation on the upper and lower surfaces of two secondary eddies in addition to the two large vortices. Furthermore, the LES properly captures the dynamics in the laminar boundary layer as reflected by the skin friction values even though it makes use of a constant coefficient Smagorinsk-y?subgrid-scale model. In the study of the transversely oscillating cylinder with two-dimensional URANS k-T Speziale simulations, the lock-in region starts at significantly lower motion fre-quencies than observed in experimental results, while the phase shift was not observed. No numerical studies close to this Reynolds number are available in the literature. and further investigation is required.

Author: Manuel D. Salas
Publisher: Springer Science & Business Media
ISBN: 9401147248
Category : Science
Languages : en
Pages : 385

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Book Description
Turbulence modeling both addresses a fundamental problem in physics, 'the last great unsolved problem of classical physics,' and has far-reaching importance in the solution of difficult practical problems from aeronautical engineering to dynamic meteorology. However, the growth of supercom puter facilities has recently caused an apparent shift in the focus of tur bulence research from modeling to direct numerical simulation (DNS) and large eddy simulation (LES). This shift in emphasis comes at a time when claims are being made in the world around us that scientific analysis itself will shortly be transformed or replaced by a more powerful 'paradigm' based on massive computations and sophisticated visualization. Although this viewpoint has not lacked ar ticulate and influential advocates, these claims can at best only be judged premature. After all, as one computational researcher lamented, 'the com puter only does what I tell it to do, and not what I want it to do. ' In turbulence research, the initial speculation that computational meth ods would replace not only model-based computations but even experimen tal measurements, have not come close to fulfillment. It is becoming clear that computational methods and model development are equal partners in turbulence research: DNS and LES remain valuable tools for suggesting and validating models, while turbulence models continue to be the preferred tool for practical computations. We believed that a symposium which would reaffirm the practical and scientific importance of turbulence modeling was both necessary and timely.

Author: Feng Gan Zhuang
Publisher: Springer
ISBN:
Category : Mathematics
Languages : en
Pages : 744

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Book Description

Author: Raphael Gotthard Harald Arlitt
Publisher: Cuvillier Verlag
ISBN: 3865373461
Category :
Languages : en
Pages : 221

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Book Description

Author: Frank T. Smith
Publisher: Springer Science & Business Media
ISBN: 3642830005
Category : Science
Languages : en
Pages : 403

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Book Description
The IUTAM Symposium on Boundary-Layer Separation, suggested by the UK National Committee of Theoretical and Applied Mechanics and supported by the International Union of Theoretical and Applied Mechanics, was held at University College London on August 26-28, 1986. The proposed theme and scope of the Symposium were designed to help to bring about the necessary interaction between experimentalists, computationalists and theoreticians for the furthering of understanding in this challenging subject. The talks and discussions were aimed at representing the very wide range and application of separating-flow phenomena, which often substantially affect the whole of fluid dynamics at medium to large Reynolds numbers, covering in particular both laminar and turbulent flow, steady or unsteady, two- or three-dimensional, small or large-scale, incompressible or compressible, external or internal, from the experimental, computational and theoretical standpoints. It was intended that about 80 scientists would participate in the Symposium, with about 25 talks being delivered, to which poster sessions with 8 contributions were added subsequently. All the speakers and poster presenters were selected by the scientific committee, although two late replacements of speakers were required. Fruitful discussions, well led by the session chairmen, took place formally after each talk and after the poster sessions and informally on other occasions including the social events. The present proceedings of the Symposium appear to reflect much of the current state of experimental, computational and theoretical work and progress in boundary-layer separation. We hope that they provide also ideas, questions and stimulation, in addition to major recent developments.