摘要:

AbstractThis paper concerns a numerical prediction method for buoyancy‐influenced flows using three‐dimensional non‐orthogonal curvilinear co‐ordinates. The numerical analysis of the transformed governing equations for thermal hydraulics is based on a Lagrangian method, in which advected physical values are evaluated by local cubic spline interpolations with third‐order accuracy in the three‐dimensional computational domain. In addition, the buoyancy and diffusion terms are discretized in the Lagrangian scheme so as to have second‐order accuracy with respect to time and space. The Neumann boundary conditions, which have been rather difficult for non‐orthogonal co‐ordinates to deal with, can be implemented by making use of normal vectors on the physical boundary surfaces and cubic spline interpolations. The developed numerical method is applied to the steady isothermal flow in a curved pipe and the unsteady stratified flow in a curved duct. Both of the predicted values are in good agreement with the experimental results and the validity of the prediction me

ISSN:0271-2091    

DOI:10.1002/fld.1650190802

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA new characteristic‐based method for the solution of the 2D laminar incompressible Navier‐Stokes equations is presented. For coupling the continuity and momentum equations, the artificial compressibility formulation is employed. The primitives variables (pressure and velocity components) are defined as functions of their values on the characteristics. The primitives variables on the characteristics are calculated by an upwind diffencing scheme based on the sign of the local eigenvalue of the Jacobian matrix of the convective fluxes. The upwind scheme uses interpolation formulae of third‐order accuracy. The time discretization is obtained by the explicit Runge–Kutta method. Validation of the characteristic‐based method is performed on two different cases: the flow in a simple cascade and the flow over a backwardfa

ISSN:0271-2091    

DOI:10.1002/fld.1650190803

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractWe consider uniform flow of a Newtonian fluid trasverse to a domain bounded by parallel planes. We investigate the possibility of introducing instabilities in this flow by the choice of inflow and outflow conditions. Some instabilities of this kind are found.

ISSN:0271-2091    

DOI:10.1002/fld.1650190804

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe aim of this paper is to give open boundary conditions for the incompressible Navier–Stokes equations. From a weak formulation in velocity–pressure variables, some natural boundary conditions involving the traction or pseudotraction and inertial terms are established. Numerical experiments on the flow behind a cylinder show the efficiency of these conditions, which convey properly the vortices downstream. Comparisons with other boundary conditions for the velocity and pressure are also perfor

ISSN:0271-2091    

DOI:10.1002/fld.1650190805

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractMultiblock methods are often employed to compute flows in complex geometries. While such methods lend themselves in a natural way to coarse‐grain parallel processing by the distribution of different blocks to different processors, in some situations a fine‐grain data‐parallel implementation may be more appropriate. A study is presented of the resolution of the Euler equations for compressible flow on a block‐structured mesh, illustrating the advantages of the data‐parallel approach. Particular emphasis is placed on a dynamic block management strategy that allows computations to be undertaken only for blocks where useful work is to be performed. In addition, appropriate choices of initial and boundary conditions that enchance solution convergence are presented. Finally, code portability between five different massively parallel computer systems is examined and an analysis of the performance results obtained on different parallel systems is

ISSN:0271-2091    

DOI:10.1002/fld.1650190806

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe flow structure around an NACA 0012 aerofoil oscillating in pitch around the quarter‐chord is numerically investigated by solving the two‐dimensional compressible N–S equations using a special matrix‐splitting scheme. This scheme is of second‐order accuracy in time and space and is computationally more efficient than the conventional flux‐splitting scheme. A ‘rigid’ C‐grid with 149 × 51 points is used for the computation of unsteady flow. The freestream Mach number varies from 0.2 to 06 and the Reynolds number from 5000 to 20,000. The reduced frequency equals 0.25–0.5. The basic flow structure of dynamic stall is described and the Reynolds number effect on dynamic stall is briefly discussed. The influence of the compressibility on dynamic stall is analysed in detail. Numerical results show that there is a significant influence of the compressibility on the formation and convection of the dynamic stall vortex. There is a certain influence of the Reynolds number on the flow structure. The average convection velocity of the dynamic stall vortex is approximately 0.348 times the

ISSN:0271-2091    

DOI:10.1002/fld.1650190807

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650190808

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650190809

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650190810

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY