摘要:

AbstractThe use of finite element methods for turbulent boundary‐layer flow is relatively recent and of limited extent.1In the present study, we extend the group variable approach of Fletcher and Fleer2,3to treat turbulent boundary layer flows with heat transfer using a two‐equation turbulence model. The main concepts in the formulations include a Dorodnitsyn‐type transformation which uses a velocity component as the transverse variable, a ‘variational’ formulation for the transformed equations using special test functions and development of a two‐equation turbulence model in terms of the turbulent kinetic energy and turbulence dissipation rate as additional field variables. Several numerical test cases have been examined comparing the results with finite difference calculations and comparing the two‐equation turbulence model with an algebraic tur

ISSN:0271-2091    

DOI:10.1002/fld.1650061102

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe present work deals with the numerical calculation of the incompressible turbulent flow around aerofoils. An orthogonal curvilinear grid of ‘C’ type is used for the solution of the time averaged equations and Reynolds stresses are modelled according to the κ‐ε turbulence model. PISO and SIMPLE algorithms are used to solve the strongly coupled system of the derived finite volume equations and convergence is improved by applying the method of variable local underrelaxation factors. Comparisons between the calculated and measured pressure distributions are presented for NACA 0012 and NACA 4412 wing sections. The formation of separation bubbles according to calculations is als

ISSN:0271-2091    

DOI:10.1002/fld.1650061103

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe space of divergence‐free vector functions with vanishing normal flux on the boundary is approximated by subspaces of finite elements having the same property. An easy way of generating basis functions in these subspaces is show

ISSN:0271-2091    

DOI:10.1002/fld.1650061104

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA thin film of low‐viscosity lubricating liquid between a solid wall and a viscous material reduces shear stress on the latter and tends to make it flow as though it were slipping along the wall. The result when the lubricated material is being squeezed out of the gap between approaching parallel plates is flow more nearly irrotational, or extensional, the more effective the lubricating film on the plates. Two Newtonian analyses of this flow situation are reported. One is an approximate, asymptotic analytical solution for Newtonian lubricating flow in the films and combined mixed flow, shear and extension, in the viscous layer. The second is a full two‐dimensional axisymmetric solution of the momentum and continuity equations along with the kinematic condition which governs the motion of the interface. Both analyses indicate that there are two limiting flow regimes, depending on the ratio of the thickness of each of the two phases to radius and on the viscosity ratio of the two liquids. In one limit the flow is parallel squeezing and the lubricant layer slowly thins and persists a long time. In the other the lubricant is expelled preferentially. Implications of the results are discussed for rheological characterization of viscoelastic liquids and for prediction of lubricated or autolubricated flows in processing situati

ISSN:0271-2091    

DOI:10.1002/fld.1650061105

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe stability of two different mixed finite element methods for incompressible flow problems are theoretically analysed. The effect of the stability of the mixed approximation on the accuracy and the rate of convergence of solution is assessed for two non‐trivial problems. The numerical results presented indicate that if the stability of the mixed approximation is not guaranteed then both pressure and velocity solutions are markedly less accurate. In one of the cases considered the ultimate convergence of both the pressure and the velocity solutions is seriously in doub

ISSN:0271-2091    

DOI:10.1002/fld.1650061106

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650061107

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650061108

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650061101

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY