摘要:

AbstractThis paper is devoted to a comparison of various iterative solvers for the Stokes problem, based on the preconditioned Uzawa approach. In the first section the basic equations and general results of gradient‐like methods are recalled. Then a new class of preconditioners, whose optimality will be shown, is introduced. In the last section numerical experiments and comparisons with multigrid methods prove the quality of these schemes, whose discretization is detaile

ISSN:0271-2091    

DOI:10.1002/fld.1650080802

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA simple, but powerful iterative technique is presented for the numerical solution of the time‐dependent flow of an incompressible viscous fluid with or without a free surface. The usual numerical stability restrictions related to the viscous acceleration terms are avoided using standard implicit differencing techniques. The properties and accuracy of the method are illustrated by several calculational example

ISSN:0271-2091    

DOI:10.1002/fld.1650080803

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA complete first‐order model and locally analytic solution method are developed to analyse the effects of mean flow incidence and aerofoil camber and thickness on the incompressible aerodynamics of an oscillating aerofoil. This method incorporates analytic solutions, with the discrete algebraic equations which represent the differential flow field equations obtained from analytic solutions in individual grid elements. The velocity potential is separated into steady and unsteady harmonic parts, with the unsteady potential further decomposed into circulatory and non‐circulatory components. These velocity potentials are individually described by Laplace equations. The steady velocity potential is independent of the unsteady flow field. However, the unsteady flow is coupled to the steady flow field through the boundary conditions on the oscillating aerofoil. A body‐fitted computational grid is then utilized. Solutions for both the steady and the coupled unsteady flow fields are obtained by a locally analytic numerical method in which locally analytic solutions in individual grid elements are determined. The complete flow field solution is obtained by assembling these locally analytic solutions. This model and solution method are shown to accurately predict the Theodorsen oscillating flat plate classical solution. Locally analytic solutions for a series of Joukowski aerofoils demonstrate the strong coupling between the aerofoil unsteady and steady flow fields, i.e. the strong dependence of the oscillating aerofoil aerodynamics on the steady flow effects of mean flow incidence angle and aerofoil camber and thic

ISSN:0271-2091    

DOI:10.1002/fld.1650080804

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA class of stable least‐square finite element methods for non‐linear hyperbolic problems is developed and some exploratory studies made. The methods are based on modifying theL2‐norm of the. residual and a related approximation to theH1‐norm of the residual. The effect of the additional terms in these residual functionals is to introduce a dissipative effect proportional to the solution gradient. This acts to stabilize the solution for non‐linear hyperbolic problems which generate shocks. Numerical results for a one‐dimensional nozzle and shock tube problem demonstrate the accuracy and stability of the method. Results are for an implicit scheme and calculations for linear, quadratic and cubic element

ISSN:0271-2091    

DOI:10.1002/fld.1650080805

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA method for computing the drag coefficient of a body in an axially symmetric, steady‐state cavitation flow is presented. A ‘vortex ring’ distribution along the wetted body surface and along the cavity interface is assumed. Since the location of the cavitation interface is unknowna priori, an iterative procedure is used, where, for the first stage, an arbitrary cavitation interface is assumed. The flow field is then solved, and by an iterative process the location of the cavitation interface is corrected. Even though the flow field is governed by the linear Laplace equation, strong non‐linearity resulting from the kinematic boundary conditions appears along the cavitation interface. An improved numerical scheme for solving the dual Fredholm integral equations is obtained by formulating high‐order approximations to the singular integrals in order to reduce the matrix dimensions. Good agreement is found between the numerical results of the present work, experimental results and other

ISSN:0271-2091    

DOI:10.1002/fld.1650080806

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe numerical solution of a single first‐order conservation equation by a least‐squares finite element method is considered. Isoparametric bilinear quadrilateral elements are used. The accuracy is studied numerically and it is shown that the discrete equations associated with nodal points on the boundaries should be modified in order to obtain an accurate numerical solut

ISSN:0271-2091    

DOI:10.1002/fld.1650080807

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA finite element technique is presented and applied to some one‐ and two‐dimensional turbulent flow problems. The basic equations are the Reynolds averaged momentum equations in conjunction with a two‐equation (k, ϵ) turbulence model. The equations are written in time‐dependent form and stationary problems are solved by a time iteration procedure. The advection parts of the equations are treated by the use of a method of characteristics, while the continuity requirement is satisfied by a penalty function approach. The general numerical formulation is based on Galerkin's method. Computational results are presented for one‐dimensional steady‐state and oscillatory channel flow problems and for steady‐state flow over a two‐dimensional back

ISSN:0271-2091    

DOI:10.1002/fld.1650080808

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe standard least‐squares finite element method for the linearized Euler equations turns out to be inaccurate. This method is studied in detail for a system of composite type, obtained by transformation of the linearized Euler equations. The shortcomings of the method are clarified and an embedding method is constructed. It is shown numerically that this new method isO(h2)‐accur

ISSN:0271-2091    

DOI:10.1002/fld.1650080809

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650080810

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650080811

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY