Enhanced mixing at inertial microscales using flow-induced flutter

Rips, Aaron; Mittal, Rajat

doi:10.1103/physrevfluids.4.054501

Cited by 9 publications

(3 citation statements)

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“…The coupled system of equations ( 10), ( 11) and ( 12) is nonlinear due to the dependence of the Jacobian operator in U * c and to the presence of ω c in front of the mass matrix term in eq. (10). A Newton method is used to solve iteratively this system of equations.…”

Section: B Global Fluid-solid Linear Stability Analysismentioning

confidence: 99%

“…Historically, these different types of vibrations were mostly observed on large-scale objects surrounded by high-speed flows -plane wings, helicopter blades, tall buildings, bridges, etc -where they put at risk the integrity of the structure. In the recent years however, several new and smaller-scale applications have been proposed that take advantage of flow-induced vibrations for energy harvesting purposes 9 or for improving the performance of small-scale mixers 10,11 and heat exchangers 12,13 . For these applications, the objective is generally to design the system so as to maximize the vibrations.…”

Section: Introductionmentioning

confidence: 99%

“…For coupled-mode flutter, a classical choice is to resort to potential flow theories 15,21,22 , such as the Theodorsen model 27 , that have encountered a great success for the computation of aeroelastic stability of aircraft 28 . However, in contrast to aircraft applications that naturally yield high-Reynolds-number flows, energy harvesting or micro-scale mixing typically involve low-to-moderate Reynolds numbers 10,11,18,[21][22][23][24][25][26] , ranging from Re = 10 1 to Re = 10 5 . For these Reynolds numbers, the validity of the potential flow assumption must be questioned, as shown by Bruno and Fransos 29 or Brunton and Rowley 30 for the case of thin plates forced in heaving or pitching motions.…”

Section: Introductionmentioning

confidence: 99%

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Flow-induced instabilities of springs-mounted plates in viscous flows: A global stability approach

Moulin

Marquet

2021

Physics of Fluids

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The linear stability of a typical aeroelastic section, consisting in a rectangular plate mounted on flexion and torsion springs, is revisited here for low-Reynolds-number incompressible flows. By performing global stability analyses of the coupled fluid-solid equations, we find four types of unstable modes related to different physical instabilities and classically investigated with separate flow models: coupled-mode flutter, single-mode flutter, and static divergence at high reduced velocity U* and vortex-induced vibrations at low U*. Neutral curves for these modes are presented in the parameter space composed of the solid-to-fluid mass ratio and the reduced velocity. Interestingly, the flutter mode is seen to restabilize for high reduced velocities thus leading to a finite extent flutter region, delimited by low-U* and high-U* boundaries. At a particular low mass ratio, both boundaries merge such that no flutter instability is observed for lower mass ratios. The effect of the Reynolds number is then investigated, indicating that the high-U* restabilization strongly depends on viscosity. The global stability results are compared to a statically calibrated Theodorsen model: if both approaches converge in the high mass ratio limit, they significantly differ at lower mass ratios. In addition, the Theodorsen model fails to predict the high-U* restabilization of the flutter mode.

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Section: B Global Fluid-solid Linear Stability Analysismentioning

confidence: 99%