Modeling of dispersion in a polymeric chromatographic monolith.
Modeling of dispersion in a polymeric chromatographic monolith.
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DOI：
10.1016/j.chroma.2012.03.005
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发表时间：
2012-05-11
期刊：
影响因子：
--
通讯作者：
Lenhoff AM
中科院分区：
文献类型：
--
作者：
Koku H;Maier RS;Schure MR;Lenhoff AM
用高分辨率电子显微镜直接成像获得的样品几何形状模拟了商业聚合物单体中的分散。利用网格-玻尔兹曼方法得到的速度场，采用并行随机游走算法对传质过程进行建模。对有限尺寸的点粒子和探针进行了研究。使用周期边界的点粒子的色散模拟结果表明，平板高度几乎随流速线性变化，这与实验观察和理论预测的较弱相关性不一致。这种差异是由于速度场中人为对称和为模拟宏观柱长而实施的周期边界的综合作用造成的。消除周期性和模拟单个块长度导致板高度对流量的函数依赖更符合随机介质的实验趋势和理论预测。模拟的板高值比实验值低，部分原因是由于实际系统中存在壁，而算法没有模拟这种效应。另一方面，对瞬态色散系数的分析和对入口和出口侧粒子位置的比较暗示了非渐近行为和强相关性，这可能是原始样品块中优先高速通道的结果。用有限尺寸的探针进行模拟的结果是，粒子轨迹经常终止于几何形状的狭窄区域。预计截留量会随着流速的增加而单调增加，这显然是由于对流的输送（将颗粒运送到阻塞点）和扩散（将这些被截留的颗粒排出）的相对贡献。总体效果非常类似于先前在腺病毒实验中观察到的流动依赖的夹持现象。
Dispersion in a commercial polymeric monolith was simulated on a sample geometry obtained by direct imaging using high-resolution electron microscopy. A parallelized random walk algorithm, implemented using a velocity field obtained previously by the lattice-Boltzmann method, was used to model mass transfer. Both point particles and probes of finite size were studied. Dispersion simulations with point particles using periodic boundaries resulted in plate heights that varied almost linearly with flow rate, at odds with the weaker dependence suggested by the experimental observations and predicted by theory. This discrepancy resulted from the combined effect of the artificial symmetry in the velocity field and the periodic boundaries implemented to emulate macroscopic column lengths. Eliminating periodicity and simulating a single block length instead resulted in a functional dependence of plate heights on flow rate more in accord with experimental trends and theoretical predictions for random media. The lower values of the simulated plate heights than experimental ones are attributed in part to the presence of walls in real systems, an effect not modeled by the algorithm. On the other hand, analysis of transient dispersion coefficients and comparison of lateral particle positions at the entry and exit hinted at non-asymptotic behavior and a strong degree of correlation that was presumably a consequence of preferential high-velocity pathways in the raw sample block. Simulations with finite-sized probes resulted in particle trajectories that frequently terminated at narrow constrictions of the geometry. The amount of entrapment was predicted to increase monotonically with flow rate, evidently due to the relative contributions to transport of convection that carries particles to choke-points and diffusion that dislodges these entrapped particles. The overall effect is very similar to a flow-dependent entrapment phenomenon previously observed experimentally for adenovirus.
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影响因子：
3.7
作者：
CHATWIN, PC;SULLIVAN, PJ
通讯作者：
SULLIVAN, PJ
影响因子：
--
作者：
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影响因子：
3.9
作者：
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通讯作者：
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影响因子：
7.4
作者：
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通讯作者：
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影响因子：
2.4
作者：
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通讯作者：
Einstein, A