摘要:

AbstractA numerical solution procedure for internal three‐dimensional viscous flow is proposed in this paper. The formulation is based on the non‐primitive variables, the vorticity and potentials, on a curvilinear grid. A new upwind difference scheme is introduced to overcome the convective instabilities arising in the central difference scheme for the vorticity transport equations, while keeping false diffusion to a minimum level. Developing flows in both straight and curved square ducts are simulated to validate the procedure. The results are compared with both experimental measurements and analytical soluti

ISSN:0271-2091    

DOI:10.1002/fld.1650120102

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper deals with the numerical solution, using finite difference methods, of the hydrodynamic and turbulence energy equations which describe wind wave and tidally induced flow.Calculations are performed using staggered and non‐staggered finite difference grids in the vertical, with various time discretizations of the production and dissipation terms in the turbulence energy equations. It is shown that the time discretization of these terms can significantly influence the stability of the solution. The effect of time filtering on the numerical stability of the solution is also considered. The form of the mixing length is shown to significantly influence the bed stress in wind wave problems.A no‐slip condition is applied at the sea bed, and the associated high‐shear bottom boundary layer is resolved by transforming the equations onto a logarithmic or log‐linear co‐ordinate system before applying the finite difference scheme.A computationally economic method is developed which remains stable even when a very fine vertical grid (over 200 points) is used with a time step of up

ISSN:0271-2091    

DOI:10.1002/fld.1650120103

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA new accurate high‐order numerical method is presented for the coupled transport of a passive scalar (concentration) by advection and diffusion.Following the method of characteristics, the pure advection problem is first investigated. Interpolation of the concentration and its first derivative at the foot of the characteristic is carried out with a fifth‐degree polynomial. The latter is constructed by using as information the concentration and its first and second derivatives at computational points on current time leveltin Eulerian co‐ordinates. The first derivative involved in the polynomial is transported by advection along the characteristic towards time levelt+ Δtin the same way as is the concentration itself. Second derivatives are obtained at the new time levelt+ Δtby solving a system of linear equations defined only by the concentrations and their derivatives at grid nodes, with the assumption that the third‐order derivatives are continuous. The approximation of the method is of sixth order.The results are extended to coupled transport by advection and diffusion. Diffusion of the concentration takes place in parallel with advection along the characteristic. The applicability and precision of the method are demonstrated for the case of a Gaussian initial distribution of concentrations as well as for the case of a steep advancing concentration front. The results of the simulations are compared with analytical solutions and some existin

ISSN:0271-2091    

DOI:10.1002/fld.1650120104

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA vertical melt column set up between an upper heating rod and a lower sample rod, i.e. the so‐called halfzone system, is a convenient experimental tool for studying convection in the melt in floating‐zone crystal growth. In order to help understand the convection observed in the melt column, a computer model has been developed to describe steady state, axisymmetrical thermocapillary flow and natural convection in the melt. The governing equations and boundary conditions are expressed in general non‐orthogonal curvilinear co‐ordinates in order to accurately treat the unknown melt/solid interface as well as all other physical boundaries in the system. The effects of key dimensionless variables on the following items are discussed: (1)convection and temperature distribution in the melt; (2) the shape of the melt/solid interface; (3) the height of the melt column. These dimensionless variables are the Grashof, Marangoni and Prandtl

ISSN:0271-2091    

DOI:10.1002/fld.1650120105

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractIn this paper, a segregated finite element scheme for the solution of the incompressible Navier‐Stokes equations is proposed which is simpler in form than previously reported formulations. A pressure correction equation is derived from the momentum and continuity equations, and equal‐order interpolation is used for both the velocity components and pressure. Algorithms such as this have been known to lead to checkerboard pressure oscillations; however, the pressure correction equation of this scheme should not produce these oscillations. The method is applied to several laminar flow situations, and details of the methods used to achieve converged solutions are gi

ISSN:0271-2091    

DOI:10.1002/fld.1650120106

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650120107

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650120108

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650120101

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY