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利用耗散粒子动力学(dissipative particle dynamics,DPD)方法模拟了微通道中高分子溶液的Poiseuille流动.研究表明,微通道中的高分子溶液呈现非牛顿流体特性,可以用幂律流体来描述流动行为,高分子浓度越大,幂律指数n越小.高分子链与壁面的流体动力学相互作用以及布朗扩散率梯度控制着高分子链的横向迁移.由于传统的DPD方法中壁面诱导的流体动力学作用部分被屏蔽,高分子链将向壁面方向迁移,并且随着流场增强,高分子链向壁面方向迁移越明显.未被屏蔽的流体动力学相互作用和布朗扩散率梯度相互竞争,使高分子链在微通道内的质心分布呈双峰状,通道中心处高分子浓度出现局部最小值.当通道宽度减小、强受限时,壁面与高分子链间的流体动力学相互作用可能全部被屏蔽,而布朗扩散运动弱,高分子向壁面方向有微弱的迁移.
The Poiseuille flow of the polymer solution in the microchannel was modeled by the dissipative particle dynamics (DPD) method. The results show that the polymer solution in the microchannel exhibits the characteristics of non-Newtonian fluid and the flow behavior can be described by power law fluid , The higher the polymer concentration, the smaller the power law index n.The hydrodynamic interaction between the polymer chain and the wall and the Brownian diffusion gradient control the lateral migration of the polymer chains.Because the wall-induced hydrodynamic force in the traditional DPD method The role of the polymer is shielded and the polymer chain will migrate toward the wall, and as the flow field increases, the migration of the polymer chains to the wall becomes more pronounced. The unshielded hydrodynamic interaction and the Brownian diffusion gradient compete with each other The centroid distribution of macromolecular chains in the microchannel is bimodal with the local minimum concentration of macromolecule in the center of the channel.When the channel width is reduced and the strong confinement is limited, the hydrodynamic interaction between the macromolecule chain and the wall may be All were shielded, while the Brownian diffusion movement was weak and the polymer migrated faintly towards the wall.