Research on Coherent Structures in a Mixing Layer of the FENE-P Polymer Solution
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摘要: 采用FENE-P模型对高雷诺数下二维粘弹性混合过程中拟序结构的演变进行了数值研究.由于对聚合物应力场采用了适当的滤波措施,得到了较AH更宽参数范围内FENE-P流体混合层流场中拟序结构的运动特性,计算结果表明:在流场中加入聚合物,基波和次谐波的发展受到抑制,涡量扩散加强,减慢了配对时两涡核的旋转运动,这种影响随Weissenberg数的增大而减小,但却随参数b的增大而加强.另外,与相同溶液粘度下的牛顿流体相比,配对过程中涡量完全合并的时刻延迟了.Abstract: The evolution of the coherent structures in a two-dimensional time-developing mixing layer of the FENE-P fluids is examined numerically.By the means of an appropriate filtering for the polymer stress,some characteristics of the coherent structures at high b were obtained,which Azaiez and Homsy did not address.The results indicate that adding polymer to the Newtonian fluids wil cause stronger vorticity diffusion,accompanied with weaker fundamental and subharmonical perturbations and slower rotational motion of neighboring vortices during pairing.This effect decreases with the Weissenberg number,but increases with b.In addition,the time when the consecutive rollers are completely coalesced into one delays in the viscoelatic mixing layer compared with the Newtonian one of the same total viscosity.
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Key words:
- mixing layers /
- coherent structures /
- FENE-P model /
- pseudo-spectral method
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