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Dynamic simulations of suspensions of rod-like polymers and colloids.

机译：棒状聚合物和胶体悬浮液的动态模拟。

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Simulations presented in this dissertation advance knowledge of the dynamics of suspensions of rigid and semi-rigid Brownian fibers. This work resolves competing claims concerning the power-law scaling for the concentration dependence of the rotational diffusivities. The power-law scaling states that the rotational diffusivity DR scales as DR/ DR0 ∼ (nL3)nu, where DR0 is the rotational diffusivity of a single fiber in infinite dilution, n is the number density (number of fibers per unit volume), and L is the fiber length. The choice of hydrodynamic model, with an intrinsic ratio of the rotational to translational diffusivities at infinite dilution L2DR0/DT0 , sets the value of the exponent nu in the scaling. The aspect ratio of the fibers also affects the scalings, with strong variations for ratios less than fifty; ratios of fifty or higher can considered infinitely thin. An analysis of the numerical integration method was performed, resulting in a new algorithm with less error and higher efficiency.; Adding flexibility delays the number density at which fibers become significantly hindered by their neighbors and enter the regime where a strong decrease in the rotational diffusivity occurs. Once within this semi-dilute regime, the power-law scalings of the semi-rigid fibers closely match those of rigid fibers with corresponding hydrodynamic models and aspect ratios. Comparing simulations of rigid and semi-rigid fibers to experimental results demonstrates that different micro-mechanical models can produce results which are indistinguishable within measurement capabilities. Consequently, proper models cannot be distinguished based solely on their rotational diffusivities, so other measures are needed to identify the appropriate model.; Including hydrodynamic interactions into the simulations will provide further insights into the dynamics of fiber suspensions. Investigations of a parallel computation of the pair interactions and Cholesky decomposition indicate that simulating systems of over one hundred fibers is feasible.
机译：本论文提出的仿真技术使人们对刚性和半刚性布朗纤维的悬浮动力学有深入的了解。这项工作解决了关于幂律定标对旋转扩散度的浓度依赖性的相互竞争的主张。幂律定标指出，旋转扩散率DR缩放为DR / DR0〜（nL3）nu，其中DR0是无限稀释的单根光纤的旋转扩散率，n是数密度（每单位体积的纤维数）， L是纤维长度。流体动力学模型的选择具有无限稀释L2DR0 / DT0时旋转扩散和平移扩散系数的内在比值，可设置缩放比例中nu的值。纤维的长径比也会影响结垢，小于50的比率会有很大变化。五十或更高的比率可以认为是无限薄的。对数值积分方法进行了分析，得出了误差少，效率高的新算法。增加柔韧性会延迟纤维的数量密度，在该密度下，纤维会被其邻居显着阻碍，并进入旋转扩散率大大降低的状态。一旦进入半稀释状态，半刚性纤维的幂律定标就与刚性纤维的幂律定标与相应的流体动力学模型和纵横比紧密匹配。将刚性和半刚性纤维的仿真与实验结果进行比较，结果表明，不同的微机械模型可以产生在测量能力内无法区分的结果。因此，不能仅根据旋转扩散率来区分适当的模型，因此需要其他措施来识别适当的模型。将流体动力学相互作用包括在仿真中将提供对纤维悬浮液动力学的进一步了解。对相互作用的并行计算和Cholesky分解的研究表明，模拟一百根以上的纤维是可行的。

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