摘要:

AbstractTwo dimensional sloshing analysis has been carried out by the Lagrangian finite element method. For the integration in time, the velocity correction method with the same interpolation functions for velocity and pressure is successfully used. The Lagrangian treatment to pursue the free surface position is presented. The comparison with the experiments shows extremely good agreement. It is shown that the large amplitude sloshing waves in a container can be analyzed by the present method.

ISSN:0271-2091    

DOI:10.1002/fld.1650110502

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA new finite element technique is developed for predicting the velocity and the pressure in transient incompressible viscous fluid flows at high Reynolds numbers. The new method is based on the generalized and simplified marker‐and‐cell method (GSMAC) and has two characteristics: one is an application of the Bernoulli function and the implicit pressure solution algorithm to the explicit fractional time step method; the other is a high‐order flux calculation to prevent the pressure field from oscillating. Two examples, driven cavity flows at high Reynolds numbers and vortex shedding behind a circular cylinder, are presented. Satisfactory agreement with experiment is demonst

ISSN:0271-2091    

DOI:10.1002/fld.1650110503

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper describes the application of the Taylor–Galerkin method to the calculation of incompressible viscous flows. A finite element fractional‐step method for the Navier–Stokes equations is combined with the Taylor–Galerkin method to achieve an accurate treatment of the convection part of the problem. A scheme of second‐order accuracy in time for the non‐linear convection written in non‐conservative form is presented. Numerical results are provided to illustrate the quality of the computed transient solutions in t

ISSN:0271-2091    

DOI:10.1002/fld.1650110504

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA review of our solution techniques for the vorticity–streamfunction formulation of two‐dimensional incompressible flows is presented. While both the viscous and inviscid cases are considered, the derivation of the proper finite element formulations for multiply connected domains is emphasized. In all formulations associated with the vorticity transport equation, the streamline upwind/Petrov–Galerkin method is used. The adaptive implicit–explicit and grouped element‐by‐element solution strategies are employed to maximize the computational efficiency. The solutions obtained in all test cases compare well with solutions from previously published investigations. The convergence and benchmark studies performed in this paper show that the solution techniques presented are accurate, reliable an

ISSN:0271-2091    

DOI:10.1002/fld.1650110505

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThree numerical examples of singular flows in two and three dimensions computed with the vortex method are presented. The effect of the cut‐off parameter is investigated and special techniques are added to the classical vortex method to diminish the numerical instabilities present in the example

ISSN:0271-2091    

DOI:10.1002/fld.1650110506

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe infinite element method is employed to approximate the solutions of Webster's horn equation and Berkhoff's equation for water wave radiation and scattering in an unbounded domain. Functionals based on the first variational principle are presented. Two new infinite elements, which exactly satisfy the one‐ and two‐dimensional Sommerfeld radiation condition, are presented; the simple shape functions are constructed on the basis of the asymptotic behaviour of the scattered wave at infinity. All the integrals in the functionals involving each infinite element are integrated analytically and, as a result, no numerical integration is required. The programming requirements and computational efficiency are essentially no different than those of the conventional finite element method. For the test cases presented, the numerical results are acceptably accurate when compared with the existing solutions and laboratory d

ISSN:0271-2091    

DOI:10.1002/fld.1650110507

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractLittle adaptive finite element work has been done in the area of viscoelastic flow in complex geometries. In this paper an adaptive finite element mesh refinement study is carried out on a Newtonian fluid and a Maxwell fluid in an axisymmetric 4:1 contraction. The error indicator used for the refinement is the local norm of the residual in an element. For the Newtonian fluid, steady improvement with refinement is seen, though this is not the case for the Maxwell fluid, which never achieves a solution of good quality.

ISSN:0271-2091    

DOI:10.1002/fld.1650110508

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractEver since the time of Chorin's classic 1968 paper on projection methods, there have been lingering and poorly understood issues related to the best—or even proper or appropriate—boundary conditions (BCs) that should be (or could be) applied to the ‘intermediate’ velocity when the viscous terms in the incompressible Navier–Stokes equations are treated with an implicit time integration method and a Poisson equation is solved as part of a ‘time step’. These issues also pervade all related methods that uncouple the equations by ‘splitting’ the pressure computation from that of the velocity—at least in the presence of solid boundaries and (again) when implicit treatment of the viscous terms is employed. This paper is intended to clarify these issues by showing which intermediate BCs are ‘best’ and why some that are not work well anyway. In particular we show thatallintermediate BCsmustcause problems related to the regularity of the solution near boundaries, but that a near‐miraculous recovery occurs such that accurate results are nevertheless achieved beyond thespuriousboundary layerintroducedby such methods. The mechanism for this ‘miracle’ is related to the existence of a higher‐order equation that is actually satisfied by the pressure. All that is required then for projection (splitting, fractional step, etc.) methods to work well is that the spurious boundary layer be thin—as has

ISSN:0271-2091    

DOI:10.1002/fld.1650110509

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractEver since the expansion of the finite element method (FEM) into unsteady fluid mechanics, the ‘consistent mass matrix’ has been a relevant issue. Applied to the time‐dependent incompressible Navier–Stokes equations, it virtually demands the use of implicit time integration methods in which full ‘velocity–pressure coupling’ is also inherent. The high cost of such (high‐quality) FEM calculations led to the development of simpler butad hocmethods in which the ‘lumped’ mass matrix is employed and the velocity and pressure are uncoupled to the maximum extent possible. Resulting computer codes were less expensive to use but suffered a significant loss of accuracy, caused by lumping the mass when the flow was advection‐dominated and accurate transport of ‘information’ was important. In the second part of this paper we re‐introduce the consistent mass matrix into some semi‐implicit projection methods in such a way that the cost advantage of lumped mass and the accuracy advantage of consistent mas

ISSN:0271-2091    

DOI:10.1002/fld.1650110510

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA velocity–vorticity formulation of the Navier–Stokes equations is presented as an alternative to the primitive variables approach. The velocity components and the vorticity are solved for in a fully coupled manner using a Newton method. No artificial viscosity is required in this formulation. The pressure is updated by a method allowing natural imposition of boundary conditions. Incompressible and subsonic results are presented for two‐dimensional laminar internal flows up to high Reynolds nu

ISSN:0271-2091    

DOI:10.1002/fld.1650110511

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY