挤出胀大流动的有限元方法研究

本文对Luo-Tanner提出的流线有限元作了重要的改进,提出了沿通过单元高斯点的流线积分本构方程的方法,迴避了速度梯度在单元边界上间断和出口处应力奇点的困难,同时减少了计算量,对比计算表明,采用压力不连续单元来加强不可压缩性限制能使计算质量和收敛性都得到显著的提高,对Maxwell流体的轴对称挤出胀大流动在Weissenberg数1.2下获得了合理的收敛解。

FINITE ELEMENT METHODS FOR THE EXTRUDATE SWELL PROBLEM

An essential improvement has been made upon the stream-line finite element method proposed by Luo-Tanner. Instead of integrating a constitutive equation along the elements' boundaries as Luo-Tanner did, one can integrate the equation along the stream lines passing through the elements' Gauss points. Thus the difficulties of discontinuous velocity gradients and the stress singularity at the exit line are avoided and the amount of computation is considerably reduced. A stricter enforcement of the incompressible constraint by adopting discontinuous representation for pressure allows one to obtain solutions with better quality and higher Weissen-berg number of the Maxwell fluid extruded from a circular die.