摘要:

AbstractAn investigation has been conducted to study the performance of a coupled solution approach for solving the fluid flow equations in body‐fitted co‐ordinates using a covariant velocity formulation. The set of discrete equations is solved using a sparse matrix variant of LU decomposition. A series of test problems have been considered to study the effects of Reynolds number, mesh skewness and grid size on the convergence rate. The coupled solution approach has been compared with a state‐of‐the‐art sequential approach. The results indicate that the coupled technique is faster by a factor of about two for reasonable grids. For severely non‐orthogonal grids the performance of the coupled solution approach deteriorates c

ISSN:0271-2091    

DOI:10.1002/fld.1650110102

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA new finite element method, the Taylor–least‐squares, is proposed to approximate the advection‐dominated unsteady advection–diffusion equation. The new scheme is a direct generalization of the Taylor–Galerkin and least‐squares finite element methods. Higher‐order spatial derivatives in the new formulation necessitate higher‐degree polynomials. Hermite cubic shape functions are used. Extensive comparisons with other methods in one dimension proved that the new scheme is a step forward in modelling this difficult problem. The method offers straightforward generalizations to higher dimensions without losing the accuracy demonstrated in one dimension, i.e. the method preserves the important property of the Taylor–Galerkin scheme of being free of numerical crosswind diffusion. Several numerical experiments were made in two dimensions and excellent results were obtained from the represent

ISSN:0271-2091    

DOI:10.1002/fld.1650110103

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe algebraic turbulent model of Baldwin and Lomax was incorporated into the incompressible full Navier–Stokes code FIDAP. This model was extensively tested in the past in finite difference codes. We believe that the incorporation of the model also into the finite element code has resulted in a practical method to compute a variety of separated turbulent 2D flows. Firstly, we use the model to compute the attached flow about an aerofoil. Next, the application of the model to separated flows is presented by computing the flows at high angles of attack up to maximum lift. It is shown that the model is capable of predicting separation, steady stall andCLmax. As a difficult test of the model we compute the laminar separation bubble development directly using the full Navier–Stokes finite element code. As far as we know, this approach has not yet been reported. The importance of using an appropriate upwinding is discussed. When possible, comparison of computed results with experiments is presented and the agreement is g

ISSN:0271-2091    

DOI:10.1002/fld.1650110104

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA new finite volume (FV) approach with adaptive upwind convection is used to predict the two‐dimensional unsteady flow in a square cavity. The fluid is air and natural convection is induced by differentially heated vertical walls. The formulation is made in terms of the vorticity and the integral velocity (induction) law. Biquadratic interpolation formulae are used to approximate the temperature and vorticity fields over the finite volumes, to which the conservation laws are applied in integral form. Image vorticity is used to enforce the zero‐penetration condition at the cavity walls. Unsteady predictions are carried sufficiently forward in time to reach a steady state. Results are presented for a Prandtl number (Pr) of 0‐71 and Rayleigh numbers equal to 103, 104and 105. Both 11 × 11 and 21 × 21 meshes are used. The steady state predictions are compared with published results obtained using a finite difference (FD) scheme for the same values ofPrandRaand the same meshes, as well as a numerical bench‐mark solution. For the most part the FV predictions are closer to the bench‐mark solution than are the FD

ISSN:0271-2091    

DOI:10.1002/fld.1650110105

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA double‐transform technique provides a semi‐analytic solution in the form of a series expansion for unsteady axisymmetric Stokes flow in the entrance region of a semi‐infinite rigid cylindrical tube. This in turn offers an appropriate bench‐mark problem for evaluating the quality of numerical approximations. To illustrate this, periodic axial flow in a circular cylinder is considered. Some aspects of the bench‐mark problem that are of interest include the reverse flow in the wall layers, the accuracy of the approximate method in different flow regimes and the mesh grading. This bench‐mark problem and the numerical study provide some insight into practical issues pertinent to the approximate solution of unsteady and per

ISSN:0271-2091    

DOI:10.1002/fld.1650110106

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA discretization method is presented for the full, steady, compressible Navier–Stokes equations. The method makes use of quadrilateral finite volumes and consists of an upwind discretization of the convective part and a central discretization of the diffusive part. In the present paper the emphasis lies on the discretization of the convective part. The solution method applied solves the steady equations directly by means of a non‐linear relaxation method accelerated by multigrid. The solution method requires the discretization to be continuously differentiable. For two upwind schemes which satisfy this requirement (Osher's and van Leer's scheme), results of a quantitative error analysis are presented. Osher's scheme appears to be increasingly more accurate than van Leer's scheme with increasing Reynolds number. A suitable higher‐order accurate discretization of the convection terms is derived. On the basis of this higher‐order scheme, to preserve monotonicity, a new limiter is constructed. Numerical results are presented for a subsonic flat plate flow and a supersonic flat plate flow with oblique shock wave–boundary layer interaction. The results obtained agree with the predictions made. Useful properties of the discretization method are that it allows an easy check of false diffusion and that it needs no tuning of p

ISSN:0271-2091    

DOI:10.1002/fld.1650110107

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650110108

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650110109

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650110101

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY