气泡在聚合物内长大过程的等温有限元模拟

Finite Element Simulation of Bubble Growth in Isothermal Liquid

针对气泡在聚合物熔体内的等温长大过程,建立了其几何模型和有限元模型;采用幂律型流体本构关系描述聚合物流变性质;对控制方程进行无量纲化处理,采用Galerkin方法对对流扩散有限元控制方程进行数值求解;采用隐式差分法对扩散方程中的时间导数项进行离散,并在每个时间步进行网格重划分,确保计算结果的可靠性。计算获得了聚合物内发泡剂浓度分布规律及不同的特征无量纲量对气泡长大过程的影响。

Finite element method was applied in the simulation of bubble growth in isothermal liquid in this paper. And the ＂cell＂ model was used to describe the bubble growth process. It was supposed that the gas in the bubble was ideal gas,and the foaming agent concentration at the bubble surface obeyed Henry＇s law. Power law constitutive equation was adopted to describe the rheology of polymer. Dimensionless control equations were obtained and the convective-diffusion equation was solved with Galerkin method. Backward Euler scheme was used to discretize time in advection-diffusion equation and grids were remeshed after each incremental time step to assure the accuracy of numerical results. The distribution regularity of foaming agent concentration in polymer was obtained and the influences of characteristic quantities on bubble growth were studied.