Fluid-Structure Interactions in Discrete Mechanics

The unification of the laws of fluid and solid mechanics is achieved on the basis of the concepts of discrete mechanics and the principles of equivalence and relativity, but also the Helmholtz–Hodge decomposition where a vector is written as the sum of divergence-free and curl-free components. The derived equation of motion translates the conservation of acceleration over a segment, that of the intrinsic acceleration of the material medium and the sum of the accelerations applied to it. The scalar and vector potentials of the acceleration, which are the compression and shear energies, give the discrete equation of motion the role of conservation law for total mechanical energy. Velocity and displacement are obtained using an incremental time process from acceleration. After a description of the main stages of the derivation of the equation of motion, unique for the fluid and the solid, the cases of couplings in simple shear and uniaxial compression of two media, fluid and solid, make it possible to show the role of discrete operators and to find the theoretical results. The application of the formulation is then extended to a classical validation case in fluid–structure interaction.

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Multi-resolution ISPH-SPH for accurate and efficient simulation of hydroelastic fluid-structure interactions in ocean engineering

Ocean Engineering ◽

10.1016/j.oceaneng.2021.108652 ◽

2021 ◽

Vol 226 ◽

pp. 108652

Author(s):

Abbas Khayyer ◽

Yuma Shimizu ◽

Hitoshi Gotoh ◽

Shunsuke Hattori

Keyword(s):

Fluid Structure Interactions ◽

Ocean Engineering ◽

Fluid Structure ◽

Efficient Simulation

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Cross-Flow Tidal Turbines with Highly Flexible Blades—Experimental Flow Field Investigations at Strong Fluid–Structure Interactions

Energies ◽

10.3390/en14040797 ◽

2021 ◽

Vol 14 (4) ◽

pp. 797

Author(s):

Stefan Hoerner ◽

Iring Kösters ◽

Laure Vignal ◽

Olivier Cleynen ◽

Shokoofeh Abbaszadeh ◽

...

Keyword(s):

Flow Field ◽

High Speed ◽

Cross Flow ◽

Speed Ratio ◽

Fluid Structure Interactions ◽

Dimensional Parameter ◽

Fluid Structure ◽

Passive Flow Control ◽

Tidal Turbines ◽

Tidal Turbine

Oscillating hydrofoils were installed in a water tunnel as a surrogate model for a hydrokinetic cross-flow tidal turbine, enabling the study of the effect of flexible blades on the performance of those devices with high ecological potential. The study focuses on a single tip-speed ratio (equal to 2), the key non-dimensional parameter describing the operating point, and solidity (equal to 1.5), quantifying the robustness of the turbine shape. Both parameters are standard values for cross-flow tidal turbines. Those lead to highly dynamic characteristics in the flow field dominated by dynamic stall. The flow field is investigated at the blade level using high-speed particle image velocimetry measurements. Strong fluid–structure interactions lead to significant structural deformations and highly modified flow fields. The flexibility of the blades is shown to significantly reduce the duration of the periodic stall regime; this observation is achieved through systematic comparison of the flow field, with a quantitative evaluation of the degree of chaotic changes in the wake. In this manner, the study provides insights into the mechanisms of the passive flow control achieved through blade flexibility in cross-flow turbines.

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A few remarks on penalty and penalty-duality methods in fluid-structure interactions

Applied Numerical Mathematics ◽

10.1016/j.apnum.2021.04.017 ◽

2021 ◽

Vol 167 ◽

pp. 1-30

Author(s):

Philippe Destuynder ◽

Erwan Liberge

Keyword(s):

Fluid Structure Interactions ◽

Fluid Structure ◽

Duality Methods

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Experimental observation of viscoelastic fluid–structure interactions

Journal of Fluid Mechanics ◽

10.1017/jfm.2017.15 ◽

2017 ◽

Vol 813 ◽

Cited By ~ 13

Author(s):

Anita A. Dey ◽

Yahya Modarres-Sadeghi ◽

Jonathan P. Rothstein

Keyword(s):

Flow Instability ◽

Reynolds Numbers ◽

Time Dependent ◽

Flexible Structure ◽

Fluid Inertia ◽

Fluid Structure Interactions ◽

Periodic Oscillations ◽

Fluid Structure ◽

Dependent Growth ◽

First Time

It is well known that when a flexible or flexibly mounted structure is placed perpendicular to the flow of a Newtonian fluid, it can oscillate due to the shedding of separated vortices. Here, we show for the first time that fluid–structure interactions can also be observed when the fluid is viscoelastic. For viscoelastic fluids, a flexible structure can become unstable in the absence of fluid inertia, at infinitesimal Reynolds numbers, due to the onset of a purely elastic flow instability. Nonlinear periodic oscillations of the flexible structure are observed and found to be coupled to the time-dependent growth and decay of viscoelastic stresses in the wake of the structure.

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