Abstract

Carbon nanotube (CNT) is very effective for disease treatment based on drug delivery to a target tissue, in which sustained drug release is undesirable. In the present study, magnetic-fluid flow effect and fluid and CNT size effects are investigated on the structural instability of a CNT conveying nanofluid under a longitudinal magnetic field. There is lack of research that evaluates the size-dependent problems using the appropriate robust non-classic theory. Therefore, in the present study size effects are captured using a combination of nonlocal elasticity theory and nonlocal couple stress theory. Governing equation of motion and related boundary conditions are derived using the Hamilton’s principle and they are solved by the Galerkin method. The Navier–Stokes equation of magnetic-fluid flow is coupled with the Euler–Bernoulli beam theory for modeling fluid-structure interaction (FSI). The CNT stability is evaluated by considering nonlocal sizing effect parameter, couple-stress sizing effect parameter, Knudsen number, magnetic field intensity, chirality of CNT, and velocity of fluid flow. Results indicate that a special CNT configuration can improve the stability by 16.2%. Additionally, increasing the couple stress sizing effect parameter can improve the system stability up to 48%. However, this value is reduced to 18% when a magnetic field is applied to the system. On the contrary, results indicate that the nonlocal sizing effect parameter reduces the critical speed and the system stability. Therefore, the couple-stress and nonlocal sizing effects have substantial roles in the stability assessment, which should be considered in the planning for a successful treatment.

摘要

碳纳米管（CNT）对于基于药物输送至目标组织的疾病治疗非常有效，其中持续释放药物是不希望的。在本研究中，研究了在纵向磁场下磁流体流动效应以及流体和CNT尺寸效应对CNT传输纳米流体的结构不稳定性的影响。缺乏使用适当的鲁棒非经典理论来评估尺寸相关问题的研究。因此，在本研究中，使用非局部弹性理论和非局部耦合应力理论相结合来捕获尺寸效应。使用汉密尔顿原理导出运动的控制方程和相关的边界条件，并通过Galerkin方法对其进行求解。磁流体流动的Navier–Stokes方程与Euler–Bernoulli束流理论相结合，用于建模流固耦合（FSI）。通过考虑非局部施胶效果参数，偶合应力施胶效果参数，克努森数，磁场强度，CNT的手性和流体流动速度来评估CNT的稳定性。结果表明，特殊的CNT配置可将稳定性提高16.2％。此外，增加耦合应力确定效果参数可以将系统稳定性提高到48％。但是，当磁场施加到系统时，此值减小到18％。相反，结果表明非局部上浆效果参数会降低临界速度和系统稳定性。因此，