摘要:

AbstractThis paper gives a review of methods where Green's theorem may be employed in solving numerically the Navier–Stokes equations for incompressible fluid motion. They are based on the concept of using the theorem to transform local boundary conditions given on the boundary of a closed region in the solution domain into global, or integral, conditions taken over it. Two formulations of the Navier–Stokes equations are considered: that in terms of the streamfunction and vorticity for two‐dimensional motion and that in terms of the primitive variables of the velocity components and the pressure. In the first formulation overspecification of conditions for the streamfunction is utilized to obtain conditions of integral type for the vorticity and in the second formulation integral conditions for the pressure are found. Some illustrations of the principle of the method are given in one space dimension, including some derived from two‐dimensional flows using the series truncation method. In particular, an illustration is given of the calculation of surface vorticity for two‐dimensional flow normal to a flat plate. An account is also given of the implementation of these methods for general two‐dimensional flows in both of the mentioned formulations and a numerical illustrati

ISSN:0271-2091    

DOI:10.1002/fld.1650090802

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractUnsteady viscous flow around a large‐amplitude and high‐frequency oscillating aerofoil is examined in this paper by numerical simulation and experimental visualization. The numerical method is based on the combination of a fourth‐order Hermitian finite difference scheme for the stream function equation and a classical second‐order scheme to solve the vorticity transport equation. Experiments are carried out by a traditional visualization method using solid tracers suspended in water. The comparison between numerical and experimental results is found to be satisfactory. Time evolutions of the flow structure are presented for Reynolds numbers of 3 × 103and 104. The influence of the amplitude and frequency of the oscillating motion on the dynamic stall is

ISSN:0271-2091    

DOI:10.1002/fld.1650090803

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe paper describes the basic components of a turbomachinery blade design system in use within Rolls‐Royce. A number of modelling aspects of the advanced computational methods in use and under development are reviewed together with areas for future research and development.A quasi‐3D blade design system which is used for both compressors and turbines is described covering through‐flow and blade‐to‐blade analysis. Various features of blade‐to‐blade analysis are discussed including the use of compatible design and analysis modes and coupled boundary layer analysis capable of handling attached and separated flow; examples are included to show capabilities. Advances being made in the development and application of Reynolds‐averaged Navier–Stokes models are covered showing capabilities with regard to loss and heat transfer prediction.A fully coupled quasi‐3D through‐flow and blade‐to‐blade analysis system is described and results presented to show basic capabilities.The need for 3D flow analysis is discussed and the elements of a 3D blade design system presented showing how this links to the traditional quasi‐3D system. Examples are given showing basic capabilities of the methods available and under development.Finally areas for future development are presented indicating the mathematical and numerical modelli

ISSN:0271-2091    

DOI:10.1002/fld.1650090804

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractA 3D Navier–Stokes solver has been developed to simulate laminar compressible flow over quadrilateral wings. The finite volume technique is employed for spatial discretization with a novel variant for the viscous fluxes. An explicit three‐stage Runge–Kutta scheme is used for time integration, taking local time steps according to the linear stability condition derived for application to the Navier–Stokes equations. The code is applied to compute primary and secondary separation vortices at transonic speeds over a 65° swept delta wing with round leading edges and cropped tips. The results are compared with experimental data and Euler solutions, and Reynolds number effects are inve

ISSN:0271-2091    

DOI:10.1002/fld.1650090805

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractSecond‐moment turbulence models focus directly on the transport equations for the Reynolds stresses rather than supposing the stress and strain fields to be directly linked via an eddy viscosity. This elaboration enables the effects of complex strains and force fields on the turbulence structure to be better captured. The paper summarizes the principal modelling strategies adopted for the unknown processes in these equations and presents the forms that have been found most useful in engineering calculations. Methods adopted for overcoming significant problems of numerical instability and lack of convergence compared with eddy‐viscosity‐based schemes are also presented. Applications involving momentum and heat transfer in complex flows are drawn from the advanced technology sectors of the power generation and aircraft indus

ISSN:0271-2091    

DOI:10.1002/fld.1650090806

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractA brief overview of classes of turbulent swirling flow in conical diffusers is given, together with a description of appropriate numerical schemes for each class. Numerical results obtained for the class of moderate swirl in a 20° diffuser and for the class of no swirl in an 8° diffuser are compared with experimental results. The results are obtained using a multi‐sweep scheme solving the full steady state time‐averaged Navier–Stokes equations. Turbulence quantities are approximated using two types of algebraic Reynolds stress model and two types ofk–ϵ model. One of the algebraic Reynolds stress models includes extra production terms associated with the Christoffel symbols in cylindrical co‐ordinates, and one of thek–ϵ models includes a swirl‐related modification to the ϵ equation. It is demonstrated that the standardk–ϵmodel gives poor prediction of the mean flow, and it is necessary to at least use the modified form or one of the two algebraic R

ISSN:0271-2091    

DOI:10.1002/fld.1650090807

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAn improved treatment for the Harten–Yee and Chakravarthy–Osher TVD numerical flux functions in general co‐ordinates is presented. The proposed formulation is demonstrated by a series of numerical experiments for three‐dimensional flows around the ONERA‐M6 wing. The numerical results indicate that it is important to use a suitable artificial compression parameter in order to obtain more accurate solutions around the leading edge of the wing. The two TVD numerical fluxes give excellent results: they capture the shock wave without numerical oscillations, they capture the rapid expansion around the leading edge sharply, they have self‐adjusting mechanisms regarding numerical viscosity and they also have

ISSN:0271-2091    

DOI:10.1002/fld.1650090808

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe unsteady incompressible Navier–Stokes equations are formulated in terms of vorticity and stream‐function in generalized curvilinear orthogonal co‐ordinates to facilitate analysis of flow configurations with general geometries. The numerical method developed solves the conservative form of the vorticity transport equation using the alternating direction implicit method, whereas the streamfunction equation is solved by direct block Gaussian elimination. The method is applied to a model problem of flow over a backstep in a doubly infinite channel, using clustered conformal co‐ordinates. One‐dimensional stretching functions, dependent on the Reynolds number and the asymptotic behaviour of the flow, are used to provide suitable grid distribution in the separation and reattachment regions, as well as in the inflow and outflow regions. The optimum grid distribution selected attempts to honour the multiple length scales of the separated flow model problem. The asymptotic behaviour of the finite differenced transport equation near infinity is examined and the numerical method is carefully developed so as to lead to spatially second‐order‐accurate wiggle‐free solutions, i.e. with minimum dispersive error. Results have been obtained in the entire laminar range for the backstep channel and are in good agreement with the available experimental data for this flow problem, prior to the onset of three‐dimensionality

ISSN:0271-2091    

DOI:10.1002/fld.1650090809

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650090810

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650090811

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY