Boger流体的松弛谱对非线性粘弹性表征的影响

Influence of Relaxation Spectra on Descriptions of Nonlinear Viscoelastic Properties in Boger Fluid

分析了一种Boger流体的松弛时间谱和该流体的粘弹性表征问题。文中采用带正约束的非线性规划方法得到了包含4个、5个、6个松弛时间的描述此Boger流体线性粘弹特性的时间谱。这些新时间谱比前文报道的含3个松弛时间的谱能更好地描述该流体的储能模量G′。用PSM模型结合这些新松弛时间谱都不能很准确地描述这个Boger流体的第一法向应力差N1的实验数据。作者提出的3r模型描述此Boger流体的N1的结果比PSM模型的计算结果更接近实验值。

The relaxation spectra and description of the viscoelastic Boger fluid were analyzed.The spectra containing four,five or six relaxation periods were obtained by nonlinear programming method with positive constraints,which were used to describe the linear viscoelastic Boger fluid.These new spectra show better capabilities in describing the storage modulus G' of the fluid than that of the spectrum with only three relaxation periods reported in the previous paper.The first normal stress difference N1 by PSM model with these new spectra do not show good agreement with the experimental data,while N1 can be fitted well by using the proposed 3r model.