摘要:

Numerical modelling of convection suitable for cell-centred finite volume methods for incompressible flow is considered. Higher-order accurate and oscillation-free solutions are obtained through flux limiting, Two improvements are discussed: the enhancement of accuracy at smooth extrema of the TVD solution, and the construction of flux limiters, which is based on polynomial interpolants in the normalized variable space. Some implementation issues are outlined. Numerical examples are provided to illustrate these advancements.

ISSN:1061-8562    

DOI:10.1080/10618569808940844

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Convection may occur in different processes, which may not depend on the buoyancy force. One of these processes is due to the surface tension gradient also known as Marangoni convection. Such convection creates a strong flow leading to instability for a fluid. Porous medium consists of solid matrix with an interconnected void filled with a fluid. A new treatment of the surface tension gradient at the free surface for a porous medium showed the occurrence of convection due to a temperature gradient normal to the free surface. It was concluded that this convection, being strong at the free surface, might create instability similar to Marangoni-Bénard phenomenon.

ISSN:1061-8562    

DOI:10.1080/10618569808940845

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The kinematic equations of motion that govern the flow of an inviscid stratified fluid are developed to investigate the evolution of a stratified starting flow.

ISSN:1061-8562    

DOI:10.1080/10618569808940846

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper describes the formulation and verification of a newly developed three dimensional sediment transport model for coastal waters. The multi-layer finite element method (Kawahara et al., 1978 and Li and Zhan, 1993) has been adopted to improve the ability for model boundary adaptation with actual coastal geometry which is essential for accurate sediment transport simulations. The incorporation of laboratory determined sediment parametric functions in the model to resolve the sediment transport mechanisms such as the bed deformation, sediment entrainment and deposition, and stratification is also emphasized. The model was applied to compute the suspended sediment conditions for an idealized case as well as a practical application in Hong Kong waters. The strong correlation revealed in the comparisons between the computed and observed results indicates that the present model can serve as an effective tool for sediment transport studies on harbor and port development and management.

ISSN:1061-8562    

DOI:10.1080/10618569808940847

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Convective flow in the annuli of rotating concentric cylinders were studied through a numerical model. The inner cylinder is heated and rotating in a range of Reynolds numbers where the effects of centrifugal acceleration and three dimensional Taylor vertices are considered negligible. The Prandtl number considered here varies from 0.01 to 1.0 and Rayleigh number varies from 103to 105. Inner cylinder rotation in the Reynolds number range of 0 to 1120 was considered. Numerical experiments show that the mean Nusselt number increases generally with Rayleigh number. For Prandtl number of the order 0.01 to 0.1, the mean Nusselt number remains fairly constant when the inner cylinder is rotated. Above a critical Rayleigh number, for Prandtl number of order 1.0, when the inner cylinder is made to rotate, the mean Nusselt number decreases through out the flow. For both stationary and rotating cylinders, the flow patterns observed in the annular space are very different for the range of Prandtl number fluids considered here. Mono-thermal plume above the stationary inner was observed for higher Prandtl number fluids while bi-thermal plume above the stationary inner cylinder was observed for lower Prandtl number fluids. When the inner cylinder is made to rotate, the thermal plume for higher and lower Prandtl number fluids moved in different direction.

ISSN:1061-8562    

DOI:10.1080/10618569808940848

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The purpose of this work is to show that a linearized implicit scheme for the flow resolution can be an efficient and accurate method for solving fluid-structure interaction. The fluid is modeled by the Euler equations in two dimensions and the structure by a one (free piston) or a two (NACA0012 airfoil) degrees of freedom system. The schemes are developed using a finite volume/finite element formulation and, stating the moving boundary problem in the space-time domain, the Riemann solver is generalized in a suitable manner. Assuming a modal decomposition for the structure's response, an analytical solution to the equation of motion is obtained.

ISSN:1061-8562    

DOI:10.1080/10618569808940849

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A fully-implicit algorithm is developed for the two-dimensional, compressible, Favre-averaged Navier-Stokes equations. It incorporates the standardk-ε turbulence model of Launder and Spalding and the low Reynolds number correction of Chien. The equations are solved using an unstructured grid of triangles with the flow variables stored at the centroids of the cells. A generalization of wall functions including pressure gradient effects is implemented to solve the near-wall region for turbulent flows using a separate algorithm and a hybrid grid. The inviscid fluxes are obtained from Roe's flux difference split method. Linear reconstruction of the flow variables to the cell faces provides second-order spatial accuracy. Turbulent and viscous stresses as well as heat transfer are obtained from a discrete representation of Gauss's theorem. Interpolation of the flow variables to the nodes is achieved using a second-order accurate method. Temporal discretization employs Euler, Trapezoidal or 3-Point Backward differencing. An incomplete LU factorization of the Jacobian matrix is implemented as a preconditioning method. The accuracy of the code and the efficiency of the solution strategy are presented for three test cases: a supersonic turbulent mixing layer, a supersonic laminar compression corner and a supersonic turbulent compression corner.

ISSN:1061-8562    

DOI:10.1080/10618569808940850

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor