针对幂律型流体,建立了气泡在有限聚合物熔体内长大过程的有限元模型。气泡内气体遵守理想气体定律,且气泡边界处发泡剂浓度与气泡内气体压强符合亨利定律。采用Galerkin方法对有限元控制方程进行求解,并编写了计算程序。采用隐式差分法对扩散方程中的时间导数项进行离散,确保了数值计算的稳定性。采用幂律型流体本构关系描述聚合物流变性质,计算了不同材料的物性参数和工艺参数对气泡长大过程的影响。
The modeling for spherical bubble growth in a limited amount of power-law liquid was presented by using finite element based numerical simulation method. The gas inside the bubble obeys the ideal gas law, and the gas concentration at the bubble surface follows Henry' s law. A computer code was programmed to solve the equations with Galerkin method. Implicit difference scheme was used to discretize time in advection-diffusion equation. The rheology of the melt was described by power-law constitutive equation. In each incremental time step, grids were remeshed to acquire more accurate numerical results. The influence of the initial bubble radius, zero-shear viscosity, diffusion coefficient, solubility coefficient and surface tension on bubble growth was studied and presented respectively.