摘要:

AbstractThe solution of the non‐linear set of equations arising from the application of the finite element method to non‐Newtonian fluid flow problems often requires large amounts of computer time. Four iteration schemes (Picard, Newton‐Raphson, Broyden and Dominant Eigenvalue method) are compared in three different flow geometries using a shear‐thinning fluid model. Points of comparison involve the computer time necessary to converge the equations, ease of implementation, radius of convergence and rate of conv

ISSN:0271-2091    

DOI:10.1002/fld.1650080202

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper presents a boundary element formulation employing a penalty function technique for two‐dimensional steady thermal convection problems. By regarding the convective and buoyancy force terms in Navier‐Stokes equations as body forces, the standard elastostatics analysis can be extended to solve the Navier‐Stokes equations. In a similar manner, the standard potential analysis is extended to solve the energy transport equation. Finally, some numerical results are included, for typical natural convection problems, in order to demonstrate the efficiency of the present m

ISSN:0271-2091    

DOI:10.1002/fld.1650080203

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractNon‐Darcy groundwater flow parameters are identified for three different flow systems. In the first system, which is essentially one‐dimensional, the parameters are determined by means of an integral method. A rectangular parametric grid is used for the identification of the non‐Darcy friction coefficients in the second system, which is two‐dimensional. The parameters in the third system, which involves a hybrid simulation of three‐dimensional flow, are optimized by adopting a constrained non‐linear programming technique. This technique combines Cauchy's steepest‐descent method together with the modeller's subjective judgement of the results at the end of each iterative step. The paper is concluded with a brief description of the additional research which is thought to be necessary before the difficulties of optimizing the non‐Darcy flow parameters

ISSN:0271-2091    

DOI:10.1002/fld.1650080204

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA numerical method is developed to solve the coupled unsteady laminar momentum and thermal boundary layers over a circular cylinder impulsively started from rest. The present non‐iterative finite difference method, which requires relatively fewer grid points in the reversed flow region than any other method, can easily handle the separating boundary layer flows. The results indicate that the present method has accuracy comparable with the earlier methods, while consuming computer time approximately one order of magnitude less.The present numerical method allowed investigation of the effect of buoyancy parameter on the starting boundary layer. The time‐dependent behaviour of the boundary layer is studied in terms of the appearance of the singularity, the distribution of skin friction and wall heat flux, and the wall position of the inflection point of the velocity profile. The transient as well as buoyancy‐dependent patterns of the streamlines and isotherms are also st

ISSN:0271-2091    

DOI:10.1002/fld.1650080205

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA method for generating irregular triangular computational grids in two‐dimensional multiply connected domains is described. A set of points around each body is defined using a simple grid generation technique appropriate to the geometry of each body. The Voronoi regions associated with the resulting global point distribution are constructed from which the Delaunay triangulation of the set of points is thus obtained. The definition of Voronoi regions ensures that the triangulation produces triangles of reasonable aspect ratios given a grid point distribution. The approach readily accommodates local clustering of grid points to facilitate variable resolution of the domain. The technique is generally applicable and has been used with success in computing triangular grids in multiply connected planar domains. The suitability of such grids for flow calculations is demonstrated using a finite element method for solution of the inviscid transonic flow over two‐ dimensional high‐lift aerofoil configura

ISSN:0271-2091    

DOI:10.1002/fld.1650080206

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIn strip theory analysis the vessel is represented by a series of 2D transverse sections. For 2D arbitrary‐shaped sections either floating in the free surface or totally submerged, a higher‐order boundary element analysis has been developed to permit determination of the associated radiation and diffraction velocity potentials.In this paper the formulation of the cited interaction problems is reworked to reflect the new capability of permitting curved boundary elements to represent the geometry and a higher‐order functional behaviour of the unknown velocity potentials over that geometry. This is in direct contrast to the usual technique of using straight‐line geometric panels and invariant behaviour of the required potentials over these simple panels.Applications to representative sections of floating ships and the fully submerged pontoon section of a semi‐submersible are presented. Within these applications the results of the standard Frank close‐fit technique, of linear panels and constant behaviour, are compared with different combinations of higher‐order representations of the geometry and the determined velocity potentials.Conclusions regarding the advantages and limitations of the procedures developed

ISSN:0271-2091    

DOI:10.1002/fld.1650080207

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe boundary integral equation method constitutes the basis of a number of computer programs used for the solution of wave‐obstacle interaction problems. For the case of obstacles in a constant depth fluid, the method assumes that the velocity potential at any point in the fluid may be represented by a distribution of Green's function sources over the immersed surface of the obstacle. Application of the obstacle kinematic boundary condition gives rise to an integral equation which may be solved, using numerical discretization, for the unknown source strength distribution function. Subsequent evaluation of the discretized velocity potential permits evaluation of the hydrodynamic interaction parameters.A series of numerical solutions have been carried out for a range of substantially rectangular obstacles, in a two‐dimensional domain, using varying levels of immersed profile discretization. The results, presented in the form of fixed and floating mode wave reflection and transmission, together with the motion response of the floating obstacle, demonstrate the significant sensitivity of the evaluated parameters to variations in the level of discretizat

ISSN:0271-2091    

DOI:10.1002/fld.1650080208

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650080209

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650080210

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650080201

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY