In this work, fluid–structure interaction (FSI) simulations, as well as non-FSI ones, are conducted to study the behavior of a functionally graded (FG) pH-sensitive micro-valve. The FEM analysis of the hydrogel is performed in ABAQUS while the fluid domain is analyzed in ANSYS fluent. To investigate the FSI and FG effects, both FSI and non-FSI simulations are performed for pH-sensitive micro-valve with homogeneous cross-linking distribution beside the FG cases. Two simulation domains are coupled by using a third-party software named MpCCI for both FSI and non-FSI simulations. For the FG hydrogel, linear and exponential property distributions are considered. The obtained results show a significant difference between the FG and homogeneous hydrogel behavior for both simulation methods. Additionally, the results emphasize that FSI consideration has a crucial role in the design of these smart devices. Especially, remarkable difference is observed for the closing pH of the micro-valve as well as the flow-rate diagrams. For example, a leakage is observed in FSI simulations for the closing pH of the non-FSI simulations that indicates the importance of the FSI effect. Finally, the effect of the cross-linking density distribution and the inlet pressure of micro-valve are studied and the results are analyzed.

中文翻译：

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功能梯度 pH 敏感水凝胶微阀中的流固耦合研究

在这项工作中，进行了流固耦合 (FSI) 模拟以及非 FSI 模拟，以研究功能梯度 (FG) pH 敏感微型阀的行为。水凝胶的有限元分析在 ABAQUS 中进行，而流体域在 ANSYS fluent 中进行分析。为了研究 FSI 和 FG 效应，对除 FG 情况外具有均匀交联分布的 pH 敏感微型阀进行 FSI 和非 FSI 模拟。两个仿真域通过使用名为 MpCCI 的第三方软件进行耦合，用于 FSI 和非 FSI 仿真。对于 FG 水凝胶，考虑了线性和指数特性分布。获得的结果表明，两种模拟方法的 FG 和均质水凝胶行为之间存在显着差异。此外，结果强调，FSI 考虑在这些智能设备的设计中起着至关重要的作用。特别是微阀的关闭pH值和流量图有显着差异。例如，在非 FSI 模拟的关闭 pH 值的 FSI 模拟中观察到泄漏，这表明 FSI 效应的重要性。最后，研究了交联密度分布和微阀入口压力的影响，并对结果进行了分析。