摘要:

AbstractIn this paper a memory integral viscoelastic equation is considered for simulating complex flows of non‐Newtonian fluids by stream tube analysis. A formalism is developed to take into account co‐deformational memory equations in a mapped computational domain where the transformed streamlines are parallel and straight. The particle‐tracking problem is avoided. Evolution in time and related kinematic quantities involved with a K‐BKZ integral constitutive model are easily taken into account in evaluating the stresses. Successive subdomains, the stream tubes, may be considered for computing the main flow in abrupt axisymmetric contractions from the wall to the central flow region. The ‘peripheral stream tube’ close to the duct wall is determined by developing a non‐conventional modified Hermite element. A mixed formulation is adopted and the relevant non‐linear equations are solved numerically by the Levenberg‐Marquardt algorithm. Although the singularity at the section of contraction is not involved explicitly, the results obtained for the peripheral stream tube clearly show the singularity effects and the extent of the recirculating zone near the salient corner. The algorithm is stable even at high flow rates and provides satisfactory solutions when compared with similar calculations

ISSN:0271-2091    

DOI:10.1002/fld.1650210502

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe flow of a solution between parallel plates is considered. The bottom plate is porous, while the top one is an impermeable solid. A computer program based on the control volume approach was developed to analyse the flow and concentration fields. The effects of the slip at the porous wall on the velocity and particle concentration distributions were investigated. It was observed that as the slip increases, the concentration on the porous wall decreases and the maximum velocity moves towards the porous wall. The concentration on the porous wall increases in the flow direction. This increase in the particle concentration along the porous wall may cause a reduction of the porosity and hence a variation in the suction rate along the porous wall. In order to take this effect into account, a linearly varying transverse velocity along the porous wall was considered. The results were compared with the data available in the literature.

ISSN:0271-2091    

DOI:10.1002/fld.1650210503

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA new numerical method for solving the axisymmetric unsteady incompressible Navier‐Stokes equations using vorticity‐velocity variables and a staggered grid is presented. The solution is advanced in time with an explicit two‐stage Runge‐Kutta method. At each stage a vector Poisson equation for velocity is solved. Some important aspects of staggering of the variable location, divergence‐free correction to the velocity field by means of a suitably chosen scalar potential and numerical treatment of the vorticity boundary condition are examined. The axisymmetric spherical Couette flow between two concentric differentially rotating spheres is computed as an initial value problem. Comparison of the computational results using a staggered grid with those using a non‐staggered grid shows that the staggered grid is superior to the non‐staggered grid. The computed scenario of the transition from zero‐vortex to two‐vortex flow at moderate Reynolds number agrees with that simulated using a pseudospectral method, thus validating the temporal accur

ISSN:0271-2091    

DOI:10.1002/fld.1650210504

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA time‐accurate least‐squares finite element method is used to simulate three‐dimensional flows in a cubic cavity with a uniform moving top. The time‐ accurate solutions are obtained by the Crank‐Nicolson method for time integration and Newton linearization for the convective terms with extensive linearization steps. A matrix‐free algorithm of the Jacobi conjugate gradient method is used to solve the symmetric, positive definite linear system of equations. To show that the least‐squares finite element method with the Jacobi conjugate gradient technique has promising potential to provide implicit, fully coupled and time‐accurate solutions to large‐scale three‐dimensional fluid flows, we present results for three‐dimensional lid‐driven flows in a cubic cavity for Reyn

ISSN:0271-2091    

DOI:10.1002/fld.1650210505

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIt is pointed out that there exists a hidden analogy between magnetohydrodynamic (MHD) and conventional computational fluid dynamic (CFD) equations. This allows the generalization of any conventional CFD code so that the effects of MHD can be accounted for. This generalization is actually made for the FLUENT CFD code. Although this generalized FLUENT code can easily be adjusted to any MHD environment, it has been specifically designed for metallurgical applications. Predictions of the code are validated against the analytical solutions for the Poiseuille‐Hartmann flow and for the shielding of magnetic field oscillations by a conducting medium (skin effect

ISSN:0271-2091    

DOI:10.1002/fld.1650210506

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650210507

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650210501

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY