Perivilli Satish, Kakhi Maziar, Stippler Erika
US Pharmacopeial Convention, 12601 Twinbrook Parkway, Rockville, Maryland, 20852-1790, USA,
Pharm Res. 2015 Apr;32(4):1304-15. doi: 10.1007/s11095-014-1534-9. Epub 2014 Nov 19.
This study investigated the influence of dip rate on USP Apparatus 3 hydrodynamics in the presence of a solid dosage form (e.g. tablet) using Computational Fluid Dynamics (CFD) simulations. The primary variables of interest were the liquid phase velocity in the computational domain and wall shear stresses on the tablet surfaces.
Geometry building and model setup were based on a number of simplifying assumptions. Computational grid-independent solutions were achieved for dip rates ranging from 5 to 10 dips per minute (dpm).
For all cases studied, the hydrodynamics exhibited a periodicity dictated by the dip rate. Cycle-to-cycle variations were found to be negligible. Higher velocities were predicted in the wake of the tablet and they peaked at midway positions both during the up- and downstrokes of the cylinder. Three sub-regions of velocity were identified inside the reciprocating cylinder. Results also showed localized vortices/recirculations specific to the up- and downstroke, in addition to local stagnation zones. The wall shear stresses and velocity magnitudes scaled proportionately with increasing dip rates while exhibiting qualitatively similar behavior in their spatial and temporal distributions.
Based on the predictions of the 2D axisymmetric CFD model, the hydrodynamics in USP Apparatus 3 is characterized by complex and periodic flow structures.
本研究使用计算流体动力学（CFD）模拟，在存在固体剂型（如片剂）的情况下，研究浸渍速率对美国药典装置3流体动力学的影响。主要关注的变量是计算域中的液相速度和片剂表面的壁面剪应力。
几何构建和模型设置基于一些简化假设。对于每分钟5至10次浸渍（dpm）的浸渍速率，获得了与计算网格无关的解。
对于所有研究的情况，流体动力学表现出由浸渍速率决定的周期性。发现循环间变化可忽略不计。在片剂尾流中预测到更高的速度，并且在圆柱体的向上和向下冲程期间，它们在中间位置达到峰值。在往复式圆柱体内确定了三个速度子区域。结果还显示了特定于向上和向下冲程的局部涡旋/再循环，以及局部停滞区域。壁面剪应力和速度大小随着浸渍速率的增加成比例缩放，同时在其空间和时间分布上表现出定性相似的行为。
基于二维轴对称CFD模型的预测，美国药典装置3中的流体动力学具有复杂的周期性流动结构特征。
