摘要:

AbstractThe first application of a spectral multi‐domain method for viscous compressible flow is presented. The method imposes a global flux balance condition at the interface so that high‐order continuity of the solution is preserved. The global flux balance is imposed in terms of a spectral integral of the discrete equations across adjoining domains. Since the discretized equations interior to each domain are solved uncoupled from each other and since the interface relation has a block structure, the solution scheme can be adapted to the particular requirement in each subdomain. To illustrate these advantages a Mach 11 shock calculation is presented to study the chemical kinetics initiated as air passes through a fully resolved shock w

ISSN:0271-2091    

DOI:10.1002/fld.1650081002

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe generation of three‐dimensional unstructured grids using the advancing‐front technique is described. This technique has been shown to be effective for the generation of unstructured grids in two dimensions.1,2However, its extension to three‐dimensional regions required algorithms to define the surface and suitable data structures that avoid excessive CPU‐time overheads for the search operations involved. After obtaining an initial triangulation of the surfaces, tetrahedra are generated by successively deleting faces from the generation front. Details of the grid generation algorithm are given, together with examples and

ISSN:0271-2091    

DOI:10.1002/fld.1650081003

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractLaminar‐turbulent transition in boundary layers involves a cascade of weak and strong instabilities. In the model considered here the first instability occurs with respect to two‐dimensional TS waves and causes streamwise, nearly periodic concentrations of vorticity. Linear stability analysis of this periodic flow leads to Floquet systems of equations. These systems support different classes of three‐dimensional disturbances which may initiate different routes to transition. Numerical solutions by use of accurate spectral methods reveal the spectrum of eigenmodes, growth rates and disturbance velocities. The characteristics of this secondary instability are in good agreement with results of experiments and computer simulations of transition. Non‐linear self‐interaction of the rapidly growing three‐dimensional disturbances can sustain or enhance the vital periodic accumulations of spanwise vorticity once their amplitude exceeds some threshold. This feedback loop is considered to be the key to the transition process. Owing to the broad‐band nature of secondary instability, however, the prediction of transition in practice requires additional insight into the ‘natural’ disturbance background. The sensitivity of the transition process to initial data in a broad band of frequencies and spanwise wave numbers poses new challenges for non‐linear theories and nu

ISSN:0271-2091    

DOI:10.1002/fld.1650081004

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractLocal control points are established within the context of algebraic grid generation. The method of generation is based upon a multidirectional assembly of multisurface transformations that incorporates the best features of tensor product and Boolean sum constructions. Upon assembly, the resultant capability is the capacity to conform precisely to prescribed boundaries while being able to manipulate the grid through a sparse net of control points.

ISSN:0271-2091    

DOI:10.1002/fld.1650081005

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe different stages of bursting and evolution of the fluctuation field in a turbulent boundary layer are governed by mechanisms that may be identified as either predominantly linear, i.e. governed by linear interaction with the mean shear flow, or non‐linear, i.e. with interaction between the fluctuation components also being important. Wave number‐frequency spectra reveal the presence of damped wave modes that may be modelled from the Orr‐Sommerfeld equation. Conditional sampled experimental data for streamwise velocity fluctuations in the wall layer obtained using the variable interval time averaging (VITA) method scale with the threshold level in a manner consistent with linearity. High‐amplitude wall pressure peaks show an approximately linear relationship with the associated vertical velocity fluctuations. Non‐linearity acts primarily in the near‐wall region where the fluctuation velocity is relatively

ISSN:0271-2091    

DOI:10.1002/fld.1650081006

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA finite volume method for solving the two‐dimensional compressible Navier‐Stokes equations is presented. Shortcomings of the direct extension to viscous flows of well known methods used for inviscid flows are demonstrated. Nevertheless, the method allows the computation of oscillation‐free shocks with only a few iterations. The double‐throat GAMM nozzle test case1is con

ISSN:0271-2091    

DOI:10.1002/fld.1650081007

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe paper describes and compares two different approaches to solving the equations of motion for fluid flow in a three‐dimensional lid‐driven cavity, when a higher‐order approximation to convective transport is employed. One is based on the traditional pressure correction approach in conjunction with a pentadiagonal ADI solver; the other follows a new unsegregated variable and FAS multigrid methodology. The results generated by both approaches, for laminar flow conditions, at Reynolds numbers of 100 and 1000 are compared with each other and with corresponding solutions obtained with a well known low‐order approximation to convection. Cross‐reference is also made to flow in a two‐dimensional cavity at the same Reyno

ISSN:0271-2091    

DOI:10.1002/fld.1650081008

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper describes the implementation of a 3D Navier‐Stokes solver within the framework of a multigrid strategy. The ability of multigrid to improve and sustain code performance over a range of mesh sizes and a variety of difficult flow problems is investigated. The code is applied to the study of the shock‐induced boundary layer separation on a channel hump, the flow in a 2D cascade of compressor blades, the secondary flow development in a linear cascade of gas turbine blades and the Eckardt backswept centrifugal impeller. In each case multigrid leads to significantly improved performa

ISSN:0271-2091    

DOI:10.1002/fld.1650081009

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractWe consider finite element methods for vorticity formulations of viscous incompressible flows. In two‐dimensional settings the familiar streamfunction‐vorticity formulation is examined. We focus on its accuracy, especially when using low‐order elements, and on its use with a variety of boundary conditions and in multiply connected domains. In three dimensions the velocity‐vorticity formulation is shown to be preferable, and a promising algorithm using this formulation is presented. We close by considering the recovery of the pressure field once the streamfunction or velocity fields are known. In particular we describe and analyse an algorithm for recovering the pressure which is based on well known methods for the primitive variable formulation and which requires no boundary conditions on the pressure at soli

ISSN:0271-2091    

DOI:10.1002/fld.1650081010

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper discusses incompressible Navier‐Stokes solution methods with an emphasis on the pseudocompressibility method. A steady‐state flow solver based on the pseudocompressibility approach is then described. This flow solver code has been used to analyse the internal flow in the Space Shuttle main engine hot‐gas manifold. Salient features associated with this three‐dimensional realistic flow simulation are discussed. Numerical solutions relevant to the current engine analysis and the redesign effort are discussed along with experimental results. This example demonstrates the potential of computational fluid dynamics as a design tool for aerospace appli

ISSN:0271-2091    

DOI:10.1002/fld.1650081011

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY