Modal analysis of wingtip vortices by means of Proper Orthogonal Decomposition

PAMM ◽  
2017 ◽  
Vol 17 (1) ◽  
pp. 693-694
Author(s):  
Sebastian Dufhaus ◽  
Sarina Brautmeier ◽  
Anna Uhl ◽  
Ralf Hörnschemeyer ◽  
Eike Stumpf
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Modal Analysis ◽  
Orthogonal Decomposition ◽  
Proper Orthogonal

Macromodeling Method of Fluid-Structure Interacting MEMS Based on Modal Analysis and Proper Orthogonal Decomposition

2007 ◽  
Author(s):  
Wentao Hao ◽  
Ling Tian ◽  
Bingshu Tong
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Orthogonal Decomposition ◽  
Mems Devices ◽  
High Complexity ◽  
Fluid Structure ◽  
Fluid Field ◽  
Speed Up ◽  
Proper Orthogonal

Because of their good performance to speed up MEMS system simulation processes, macromodels have aroused lots of attentions of scientists in the last decades. However, studies on FSI (Fluid-Structure Interaction) MEMS devices still can not satisfy the macromodeling requests because of the high complexity of fluid fields. A new method based on modal analysis and POD (Proper Orthogonal Decomposition) is tentatively put forward to reduce the order of FSI MEMS models. The structure macromodeling theory is firstly reviewed. Then the fluid field macromodeling approach is discussed in detail. At last, a 2D fixed-fixed micro-beam is analyzed and the results show that the macromodel extracted in this method can highly decrease the system degrees of freedom, while its precision is still comparable with that of detailed models.

Enhanced Proper Orthogonal Decomposition for the Modal Analysis of Homogeneous Structures

2002 ◽  
Vol 8 (1) ◽  
pp. 19-40 ◽  
Author(s):  
S. Han ◽  
B. F. Feeny
Keyword(s):  
Finite Element ◽  
Proper Orthogonal Decomposition ◽  
Modal Analysis ◽  
Normal Modes ◽  
Orthogonality Condition ◽  
Orthogonal Decomposition ◽  
Analysis Tool ◽  
Homogeneous Structures ◽  
Proper Orthogonal ◽  
Modal Coordinates

Proper orthogonal decomposition (POD) is studied in an effort to increase its applicability as a modal analysis tool. A modification is proposed to make better use of spatial resolution and to accommodate arbitrary spacing in the discretization. The theory for this modification is rooted in the discrete approximation of the integral orthogonality condition for continuous normal modes. The modified POD is applied to a finite element beam and an experimental beam sensed with accelerometers, and the resulting proper orthogonal modes (POMs) are compared to the theoretical modes of the beam. The POMs are used as a basis for decomposing the signal ensemble into proper modal coordinates. The proper modal coordinates are used to evaluate the POMs and to match modes with modal frequencies and damping.

scholarly journals Lagrangian approach for modal analysis of fluid flows

2021 ◽  
Vol 928 ◽  
Author(s):  
Vilas J. Shinde ◽  
Datta V. Gaitonde
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Modal Analysis ◽  
Lyapunov Exponents ◽  
Finite Time ◽  
Orthogonal Decomposition ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Finite Time Lyapunov Exponents ◽  
Mode Decomposition ◽  
Proper Orthogonal

Common modal decomposition techniques for flow-field analysis, data-driven modelling and flow control, such as proper orthogonal decomposition and dynamic mode decomposition, are usually performed in an Eulerian (fixed) frame of reference with snapshots from measurements or evolution equations. The Eulerian description poses some difficulties, however, when the domain or the mesh deforms with time as, for example, in fluid–structure interactions. For such cases, we first formulate a Lagrangian modal analysis (LMA) ansatz by a posteriori transforming the Eulerian flow fields into Lagrangian flow maps through an orientation and measure-preserving domain diffeomorphism. The development is then verified for Lagrangian variants of proper orthogonal decomposition and dynamic mode decomposition using direct numerical simulations of two canonical flow configurations at Mach 0.5, i.e. the lid-driven cavity and flow past a cylinder, representing internal and external flows, respectively, at pre- and post-bifurcation Reynolds numbers. The LMA is demonstrated for several situations encompassing unsteady flow without and with boundary and mesh deformation as well as non-uniform base flows that are steady in Eulerian but not in Lagrangian frames. We show that application of LMA to steady non-uniform base flow yields insights into flow stability and post-bifurcation dynamics. LMA naturally leads to Lagrangian coherent flow structures and connections with finite-time Lyapunov exponents. We examine the mathematical link between finite-time Lyapunov exponents and LMA by considering a double-gyre flow pattern. Dynamically important flow features in the Lagrangian sense are recovered by performing LMA with forward and backward (adjoint) time procedures.

scholarly journals Vortex Induced Vibrations Analysis of a Cantilevered Blunt Plate by Proper Orthogonal Decomposition of TR-PIV and Structural Modal Analysis

2020 ◽  
Author(s):  
Yann Watine ◽  
Céline Gabillet ◽  
Jacques-André Astolfi ◽  
Laetitia Pernod ◽  
Boris Lossouarn ◽  
...  
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Modal Analysis ◽  
Vortex Shedding ◽  
Structural Response ◽  
Reynolds Numbers ◽  
Orthogonal Decomposition ◽  
Vortex Street ◽  
Mechanical Resonance ◽  
Von Karman ◽  
Proper Orthogonal

Abstract The present work focuses on the experimental characterization of the vortex shedding and on the induced vibrations of a cantilevered blunt rectangular aluminum plate of chord to thickness ratio 16, immersed in a uniform water flow in the hydrodynamic tunnel of the French Naval Academy Research Institute. Experiences have been conducted for Reynolds numbers Re (based on chord length) ranging from 2.5 × 105 to 10.5 × 105 at zero degrees incidence. Special attention has been paid to the interaction of the structural response and the flow dynamics at the twisting resonance. For this purpose, wake structures have been analyzed by Time Resolved Particle Image Velocimetry (TR-PIV) and the structural response of the plate has been examined by laser vibrometry. The von Karman vortex street has been characterized by statistical analysis and Proper Orthogonal Decomposition of PIV velocity fields and the structure is analyzed through modal analysis. The near-wake’s structure has been examined for three different Reynolds numbers: (i) at Re = 3.0 × 105, corresponding to vortex induced structural response at constant Strouhal number; (ii) at Re = 4.5 × 105, corresponding to mechanical resonance but dissociated vortex shedding and (iii) at Re = 5.4 × 105, corresponding to lock-in of the vortex shedding at the mechanical resonance. At Re = 4.5 × 105, at mechanical resonance, it reveals the occurrence of an energy transfer between the shear layer and the bubble wake vortex which cancels synchronization of the structural vibration with the von-Karman vortex street.

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