摘要:

AbstractIn a previous work we solved numerically the steady‐state motion of an ideal fluid that fills a moving cylindrical container with partitions, and were able to compute the equivalent moments of inertia.Here we extend this work in two steps. First we introduce time dependence and then free surfaces, and are able to compute the transient motion of the fluid not filling the container. The main body of the work has to do with the treatment of free surfaces. Our approach is an extention to three dimensions of the volume of fluid method of Hirt and Nichols. The solution algorithm is outlined, and two examples that demonstrate its capability are presente

ISSN:0271-2091    

DOI:10.1002/fld.1650070602

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper presents the application of a preconditioned conjugate‐gradient‐like method to a non‐self‐adjoint problem of interest in underground flow simulation. The method furnishes a reliable iterative solution scheme for the non‐symmetric matrices arising at each iteration of the non‐linear time‐stepping scheme. The method employs a generalized conjugate residual scheme with nested factorization as a preconditioner. Model runs demonstrate significant computational savings over direct sparse m

ISSN:0271-2091    

DOI:10.1002/fld.1650070603

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractAn adaptive grid generation technique based on modified variational principles coupled with an exponential clustering has been developed and tested successfully for the computation of steady inviscid transonic projectile aerodynamics. The isoperimetric problem for adaptive gridding is to extremize a grid smoothness functional subject to grid orthogonality and resolution functionals; however, the Lagrange multipliers have been assumed to be variables with zero variation and are properly chosen as functions of local grid size to enhance locally the grid resolution as well as to maintain the weight of three grid characteristics the same over the entire flow field. With computed pressure gradient as the control function for grid adaptation, the resulting Euler equations cannot provide sufficient grid resolution in the boundary layer region of the projectile geometry; hence, a clustering technique is needed to redistribute the points along the normal grid lines. A grid generation code has been developed and coupled to an axisymmetric thin‐layer Navier‐Stokes code for self‐adaptive grid generation. For the three transonic flow cases considered,M∞= 0.91, 0.96 and 1.10, the distribution of surface pressure calculated from the inviscid option of the Navier‐Stokes code is indeed in excellent agreement with published meas

ISSN:0271-2091    

DOI:10.1002/fld.1650070604

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractAn application and an extension (to complex variables) of the classical augmented Lagrangian method is performed. Finite element computations are realized in the two‐dimensional case of an harmonic Navier‐Stokes problem with periodic boundary conditions. A formulation (extended from the traditional Stokes problem) involving a simple Lagrangian, solved by the Uzawa algorithim, was previously used.1This treatment proved unsatisfactory for large frequencies. The efficient and well‐known augmented Lagrangian technique solved by the Uzawa algorithm is used to overcome these shortcomings. Other, better techniques could be used. Nevertheless the simple method used here is efficient. Moreover the numerical implementation needs little memory storage, which is an important factor in this particular case. The well‐known conditioning technique employed is shown to be well‐adapted in this case, a fact which emerges from the study of the non‐symmetric problem involved. Finally, many tests, computations and experimental data ar

ISSN:0271-2091    

DOI:10.1002/fld.1650070605

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe piecewise linear method (PLM) based on time operator splitting is used to solve the unsteady compressible Euler equations describing the two‐dimensional flow around and through a straight wall inlet placed stationary in a rapidly rotating supersonic flow. The PLM scheme is formulated as a Lagrangian step followed by an Eulerian remap. The inhomogeneous terms in the Euler equations written in cylindrical coordinates are first removed by Sod's method and the resulting set of equations is further reduced to two sets of one‐dimensional Lagrangian equations, using time operator splitting. The numerically generated flow fields are presented for different values of the back pressure imposed at the downstream exit of the inlet nozzle. An oblique shock wave is formed in front of the almost whole portion of the inlet entrance, the incoming streamlines being deflected towards the higher pressure side after passing through the oblique shock wave and then bending down to the lower pressure side. A reverse flow appears inside the inlet nozzle owing to the recovery pressure of the incoming streams being lower than the back pressure of the inlet noz

ISSN:0271-2091    

DOI:10.1002/fld.1650070606

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractOperator splitting in the presence of source terms is necessary in order to apply Harten's second‐order accurate, total‐variation‐diminishing (TVD), shock‐capturing scheme to higher‐dimensional problems. By employing Godunov boundary treatment at the muzzle brake, such splitting is applied to the problem of muzzle brake flow simulation for the case of blasts which are impeded, by vertical and slanted baffles, respectively. Results from numerical studies of various types of wall boundary condition treatment which are consistent with Harten's TVD scheme are

ISSN:0271-2091    

DOI:10.1002/fld.1650070607

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper discusses aspects of vectorizing a recently developed calculation procedure for multidimensional recirculating fluid flows. The solution algorithm uses a coupled Gauss‐Seidel relaxation operator in conjunction with the multigrid technique. The vectorization is performed on a CRAY X‐MP/48 using a single processor. In this paper, the vectorization techniques used and the observed speed‐ups are presented for a model problem of laminar flow in a two‐dimensional square cavity. Large scale calculations with up to one quarter of a million finite difference cells (512 x 512) have been made in 45s of C

ISSN:0271-2091    

DOI:10.1002/fld.1650070608

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650070609

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650070610

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650070601

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY