摘要:

AbstractA multigrid acceleration technique developed for solving the three‐dimensional Navier–Stokes equations for subsonic/transonic flows has been extended to supersonic/hypersonic flows. An explicit multistage Runge–Kutta type of time‐stepping scheme is used as the basic algorithm in conjunction with the multigrid scheme. Solutions have been obtained for a blunt conical frustum at Mach 6 to demonstrate the applicability of the multigrid scheme to high‐speed flows. Computations have also been performed for a generic High‐Speed Civil Transport configuration designed to cruise at Mach 3. These solutions demonstrate both the efficiency and accuracy of the present scheme for computing high‐speed viscous flows over configurations of pract

ISSN:0271-2091    

DOI:10.1002/fld.1650171002

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractEight numerical schemes (first‐order upstream finite difference, MacCormack, explicit Taylor–Galerkin, random choice, flux‐corrected transport, ENO, TVD, and Euler–Lagrange methods) are compared on the basis of their computational efficiency for one‐dimensional non‐linear convection–diffusion problems. For the ideal chromatographic equation for which an exact solution exists, errors plotted against computational times show that the best methods are the random choice, Euler–Lagrange and flux‐corrected MacCormack methods. Even when significant diffusion is added to the model, steep gradients are possible because of non‐linearities. In such an instance, the random choice and flux‐corrected transport methods give the best performance. One can now tackle more complicated problems and refer to this comparative study in order to choose an adequate numerical method which will provide sufficiently accurate results

ISSN:0271-2091    

DOI:10.1002/fld.1650171003

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn extending high‐resolution methods from the scalar case to systems of equations there are a number of options available. These options include working with either conservative or primitive variables, characteristic decomposition, two‐step methods, or component‐wise extension. In this paper, several of these options are presented and compared in terms of economy and solution accuracy. The characteristic extension with either conservative or primitive variables produces excellent results with all the problems solved. Using primitive variables, the two‐step formulation produces high‐quality results in a more economical manner. This method can also be extended to multiple dimensions without resorting to dimensional splitting. Proper selection of limiters is also important in non‐characteristic extension

ISSN:0271-2091    

DOI:10.1002/fld.1650171004

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe development of a multigrid solution algorithm for the computation of three‐dimensional laminar fully‐elliptic incompressible flows is presented. The procedure utilizes a non‐orthogonal collocated arrangement of the primitive variables in generalized curvilinear co‐ordinates. The momentum and continuity equations are solved in a decoupled manner and a pressure‐correction equation is used to update the pressures such that the fluxes at the cell faces satisfy local mass continuity. The convergence of the numerical solution is accelerated by the use of a Full Approximation Storage (FAS) multigrid technique. Numerical computations of the laminar flow in a 90° strongly curved pipe are performed for several finite‐volume grids and Reynolds numbers to demonstrate the efficiency of the present numerical scheme. The rates of convergence, computational times, and multigrid performance indicators are reported for each case. Despite the additional computational overhead required in the restriction and prolongation phases of the multigrid cycling, the superior convergence of the present algorithm is shown to result in significantly reduced overa

ISSN:0271-2091    

DOI:10.1002/fld.1650171005

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractTwo‐dimensional solitary waves generated by disturbances moving near the critical speed in shallow water are computed by a time‐stepping procedure combined with a desingularized boundary integral method for irrotational flow. The fully non‐linear kinematic and dynamic free‐surface boundary conditions and the exact rigid body surface condition are employed. Three types of moving disturbances are considered: a pressure on the free surface, a change in bottom topography and a submerged cylinder. The results for the free surface pressure are compared to the results computed using a lower‐dimensional model, i.e. the forced Korteweg–de Vries (fKdV) equation. The fully non‐linear model predicts the upstream runaway solitons for all three types of disturbances moving near the critical speed. The predictions agree with those by the fKdV equation for a weak pressure disturbance. For a strong disturbance, the fully non‐linear model predicts larger solitons than the fKdV equation. The fully non‐linear calculations show that a free surface pressure generates significantly larger waves than that for a bottom bump with an identical non‐dimensional forcing function in the fKdV equation. These waves can be very steep and break either upstream or downstream

ISSN:0271-2091    

DOI:10.1002/fld.1650171006

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650171007

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650171008

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650171001

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY