Global dynamics of fluid conveying nanotubes

Ghayesh, Mergen H.; Farokhi, Hamed; Farajpour, Ali

doi:10.1016/j.ijengsci.2018.11.003

Cited by 67 publications

(16 citation statements)

References 87 publications

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“…As seen in the figure, a Cartesian coordinate frame with axes x and z is employed to describe the geometrical properties of the microsystem. In the present work, the effects of geometric nonlinearity [34][35][36][37][38][39][40][41] are considered. Accounting for the geometric nonlinearities caused by large deformations, the axial strain of the microtube (ε xx ) can be written as:…”

Section: Fluid-structure Interaction Model Of the Microtubementioning

confidence: 99%

Mechanics of Fluid-Conveying Microtubes: Coupled Buckling and Post-Buckling

2019

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This paper investigates the coupled mechanics of a fluid-conveying microtube embedded inside an elastic medium and subject to a pretension. The fluid-structure interaction model of the microsystem is developed based on Lagrange’s equations for the open system of a clamped-clamped microtube. A continuation model is used to examine the nonlinear mechanics of this microsystem prior to and beyond losing stability; the growth and the response in the supercritical regime is analysed. It is shown that the microtube stays stable prior to losing stability at the so-called critical flow velocity; beyond that point, the amplitude of the buckled microsystem grows with the velocity of the flowing fluid. The effects of different system parameters such as the linear and nonlinear stiffness coefficients of the elastic medium as well as the length-scale parameter and the slenderness ratio of the microtube on the critical speeds and the post-buckling behaviour are analysed.

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Section: Fluid-structure Interaction Model Of the Microtubementioning

confidence: 99%

Mechanics of Fluid-Conveying Microtubes: Coupled Buckling and Post-Buckling

2019

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“…The results showed that the boundary layer separation could be delayed, which led to a remarkable drag reduction and a significant improvement in the structural stability. In addition, in recent years, the study of fluid-conveying tubes has also received more and more attention from researchers [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Steady-Suction-Based Flow Control of Flutter of Long-Span Bridge

et al. 2020

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Featured Application: In this work, the effect of steady-suction-based flow control method on flutter performance of long-span bridges was studied by wind tunnel tests. This work can assist the application of this method in practical engineering. Abstract:The present wind tunnel study focuses on the effects of the steady-suction-based flow control method on the flutter performance of a 2DOF bridge deck section model. The suction applied to the bridge model was released from slots located at the girder bottom. The suction rates of all slots along the span were equal and constant. A series of test cases with different combinations of suction slot positions, suction intervals, and suction rates were studied in detail for the bridge deck model. The experimental results showed that the steady-suction-based flow control method could improve the flutter characteristics of the bridge deck with a maximal increase in the critical flutter speed of up to 10.5%. In addition, the flutter derivatives (FDs) of the bridge deck with or without control were compared to investigate the fundamental mechanisms of the steady-suction-based control method. According to the results, installing a suction control device helps to strengthen aerodynamic damping, which is the primary cause for enhanced flutter performance of bridge decks.

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“…This indicates that considering the material length scale is necessary to make sure that the results are compatible with the experimental tests. Consequently, scale-free formulations disregarding the size-dependent characteristics of ultrasmall systems are not reliable [34]. To capture the influence of such phenomena, a modified continuum mechanics theory was developed.…”

Section: Introductionmentioning

confidence: 99%

On the dynamics of micro-tubes conveying fluid on various foundations

2019

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In this paper, using modified couple stress theory, dynamic stability of a cantilevered micro-tube embedded in several types of elastic media is studied. The governing equation for lateral vibrations of the micro-tube conveying fluid is derived using the extended Hamilton's principle. The numerical results are obtained by employing the extended Galerkin's method. For validation purposes, the obtained results for simple cases are compared and findings indicate a very good agreement with those available in the literature. The stability maps of different configurations with different flow velocities are studied and the influences of various parameters such as material length scale, external diameter and different elastic properties on the stability of the system are considered. Results indicate that elastic environments may enlarge the stability regions significantly at larger values of mass ratio parameter while decrease it for smaller values of mass ratio parameter. Moreover, using elastic media mathematically defined by series functions provides the capability to simulate almost any real time operational environment the micro-tube embedded in and results in an optimal stability state of the micro-structure carrying fluid flow.

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Global dynamics of fluid conveying nanotubes

Cited by 67 publications

References 87 publications

Mechanics of Fluid-Conveying Microtubes: Coupled Buckling and Post-Buckling

Mechanics of Fluid-Conveying Microtubes: Coupled Buckling and Post-Buckling

Steady-Suction-Based Flow Control of Flutter of Long-Span Bridge

On the dynamics of micro-tubes conveying fluid on various foundations

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