Pharyngeal bolus flow was simulated numerically using a finite element method. The bolus liquids were X-ray medium, glucose, and thickener solutions. For a low-viscosity bolus, the simulation showed reasonable agreement of bolus velocity with X-ray measurements. The influence of bolus density on swallowing velocity was investigated numerically. Although a higher density resulted in a higher bolus velocity, the increase in velocity was modest. When the bolus viscosity was high, it was necessary to apply the slip boundary condition to obtain agreement for bolus velocity between the simulation and X-ray measurements. The simulations also showed that the method of characteristic shear rate proposed by Zhu et al. (2014) is effective for predicting the bolus velocity for shear thinning fluids. In order to discuss the effect of saliva lubrication and the physical meaning of the characteristic shear rate, an immiscible two-layer flow of the core and wall layer was analyzed theoretically by analogy with mesopharyngeal bolus flow. The characteristic shear rate enabled us to correlate the macroscopic flow behavior and the viscosity of the core layer fluid. Lubrication due to the wall layer caused apparent slip and enhanced the transfer of viscous core fluid. For viscous fluid that presented a large apparent slip in the two-layer model, the slip boundary condition was needed in the swallowing simulation. The numerical simulation and model flow analysis revealed the usefulness of characteristic shear rate and the importance of saliva-layer lubrication in swallowing. This article is protected by copyright. All rights reserved.

中文翻译：

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药丸粘度和表观滑移对咽药丸流量影响的数值模拟

使用有限元方法以数值方式模拟咽药丸流。推注液体是 X 射线介质、葡萄糖和增稠剂溶液。对于低粘度推注，模拟显示推注速度与 X 射线测量值的合理一致性。数值研究了丸剂密度对吞咽速度的影响。尽管较高的密度导致较高的推注速度，但速度的增加是适度的。当团注粘度高时，需要应用滑动边界条件来获得模拟和 X 射线测量之间的团注速度的一致性。模拟还表明，朱等人提出的特征剪切速率方法。(2014) 可有效预测剪切稀化流体的推注速度。为了讨论唾液润滑的作用和特征剪切速率的物理意义，通过类比食道丸流，从理论上分析了核壁层不混溶的两层流。特征剪切速率使我们能够关联宏观流动行为和核心层流体的粘度。由于壁层的润滑引起了明显的滑移并增强了粘性核心流体的传递。对于在两层模型中表现出较大明显滑移的粘性流体，吞咽模拟中需要滑移边界条件。数值模拟和模型流动分析揭示了特征剪切速率的有用性和唾液层润滑在吞咽中的重要性。本文受版权保护。版权所有。