PIV measurements combined with the motion tracking technique to analyze flow around a moving porous structure

Druault, Philippe; Germain, Grégory; Facq, Jean-Valéry

doi:10.1016/j.jfluidstructs.2015.04.004

Cited by 14 publications

(9 citation statements)

References 22 publications

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“…Due to the flexibility and the small thickness of the structure, a motion tracking technique allowing the measurement of the instantaneous motion of the deformable fishing net during PIV measurements is used. This technique detailed in [14] allows to track the motion of reference points (0.8cm diameter solid balls) visible in each PIV frame. Note that the targets are not in the main symmetrical axis of the piece of net in order to not disturb the flow measurement made in parallel.…”

Section: Piv Measurement Systemmentioning

confidence: 99%

Phase-averaged mean properties of turbulent flow developing around a fluttering sheet of net

Bouhoubeiny

Druault

Germain³

2014

Ocean Engineering

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Time-Resolved Particle Image Velocimetry (PIV) measurements are performed to investigate the hydrodynamic flow interaction with a representative piece of fishing net structure. Using the advanced post-processing mathematical tool based on Proper Orthogonal Decomposition, the phase averaged mean properties of turbulent flows are extracted from PIV database, demonstrating the existence of a Turbulent Boundary Layer (TBL) flow developing all around the sheet of net. The results also show that the mesh opening and so the turbulent flow passing through the structure are strongly influenced by the structure oscillations. This work allows us to demonstrate that the drag computation of fishing gear, commonly based on uniform velocity, needs to consider not only the local velocity deficit near the horizontal part of the net but also the instantaneous oscillations of the sheet of net. Highlights► We provide a better understanding of the flow through netting structures. ► We show the development of Turbulent Boundary Flow around horizontal net structure. ► We demonstrate the great influence of fluttering net structure onto hydrodynamics. ► Such study will help to improve the fishing gears drag computation.

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Section: Piv Measurement Systemmentioning

confidence: 99%

Phase-averaged mean properties of turbulent flow developing around a fluttering sheet of net

Bouhoubeiny

Druault

Germain³

2014

Ocean Engineering

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“…Indeed, the codend hydrodynamics have as a non-negligible impact on its selection [1]. For instance, the codend fluttering motions lead to some changes in the codend mesh openings [2,3,4] and may have direct consequences on cleaner catches, knowing that the catch is correlated to the codend behavior [5,6,7]. The analysis of the high Reynolds turbulent flow around a moving codend remains a challenge for both experimental and numerical approaches.…”

Section: Introductionmentioning

confidence: 99%

Analysis of hydrodynamics of a moving trawl codend and its fluttering motions in flume tank

Druault

Germain

2016

European Journal of Mechanics - B/Fluids

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The coupled dynamics of the codend fluttering motion and its hydrodynamics behavior are investigated based on PIV measurements carried out around a 1/10 scaled model codend. The mean wake flow characteristics are firstly analyzed demonstrating the great effect of the codend motion. The differences in flow contour between fluttering motion and no-fluttering codend are highlighted by analyzing the classical mean characteristics of a body wake flow. In presence of fluttering motion, the classical results are recovered only if one considers the vertical extent of the codends oscillations as a reference length scale. Secondly, the frequency content of codend oscillations is analyzed and it is linked to the physical mechanisms. It is observed that the motion of the codend is mainly of a low-frequency activity and of another component related to the vortex shedding street. It is then demonstrated a complex fluidstructure interaction where the near wake hydrodynamics of the moving codend structure are an intricate interplay between the codend fluttering motion and the shear layer instabilities and large scale vortex shedding. The knowledge of such flow instabilities is of great importance to improve the understanding of the force acting on a trawl and for the implementation of some selected device to drive fish near the codend and then to reduce juvenile by-catch.

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“…The development of the unsteady turbulent flow can be also explained by the fact that the presence of the catch inside the trawl net increased the transverse and longitudinal motions, and considerably modified the mesh opening, resulting in a decrease in the flow passage 6 , 24 , 25 . The notion that the velocity reduction increased with decreasing tilt angle and mesh opening was demonstrated in the flow study around the fishing net by Bouhoubeiny et al 25 , Druault et al 20 , and Bi et al 48 . This trend was also confirmed by the study of the turbulent flow around the bottom trawl net by Druault et al 24 , and Thierry et al 14 .…”

Section: Discussionmentioning

confidence: 87%

“…The analysis of the complex interaction between unsteady turbulent flow and the moving trawl structure including catch is a fundamental scientific topic that has drawn increased attention and studies in scientific research in both simulation and experimental work 20 – 22 . This analysis provides a better understanding of the flow behavior and oscillatory motions of the trawl net, thus affords relevant information for the analysis of hydrodynamic forces and selectivity via the fish response, such as the herding response or escape behavior 10 , 14 .…”

Section: Introductionmentioning

confidence: 99%

“…Kim 10 , 30 analysed the turbulent flow inside the trawl codend during the sea trial by performing one-point measurements using the 3D Acoustic Doppler Velocimeter (ADV) and demonstrating that the presence of the turbulent flow inside the trawl codend affected the fish behavior. Druault et al 20 , 24 and Bouhoubeiny et al 25 used time-resolved particle image velocimetry (TRPIV) combined with a motion tracking technology for the measurement of the instantaneous motion of the mean flow field from unsteady turbulent flow developing around random oscillated structure deformable fishing net and bottom trawl to investigate the turbulent boundary layer flow. They demonstrated the feasibility of the Proper Orthogonal Decomposition (POD) procedure to extract the instantaneous mean flow field and confirmed that the transverse and longitudinal oscillations of the fishing net and trawl structure induce opening variability which may have a significant effect on the escape of fish and the engineering performance of the trawl net.…”

Section: Introductionmentioning

confidence: 99%

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Turbulent flow interacting with flexible trawl net structure including simulation catch in flume tank

Thierry

Tang

Liu

et al. 2023

Sci Rep

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The interaction between fluid and the midwater trawl with stocked catches is extremely complex, but essential to improve the understanding of the drag force acting on the trawl, the behavior of the fishing structure during a trawling process, and to predict its selectivity process. The present study assesses the turbulent characteristics inside and around the midwater trawls with catch and without catch linked to its fluttering motion. The analysis is based on three-dimensional electromagnetic current velocity meter measurements performed in the multiple points inside and outside different parts of a 1/35 scaled midwater trawl model with the aim of access the main turbulent flow structure inside and around the gear. Time-averaged normalized flow velocity fields and turbulent flow parameters were analyzed from the measured flow data. Furthermore, Fourier analysis was conducted by watching the time–frequency Power spectrum content of instantaneous flow velocities fields, the fluttering trawl motions, turbulent kinetic energy, and momentum flux. Based on successive analyzes of mean flow characteristics and turbulent flow parameters, it has been demonstrated that the presence of catch inside the trawl net impacts the evolution of unsteady turbulent flow by creating large trawl fluttering motions that strongly affect the flow passage. The results showed that the time-averaged normalized streamwise and transverse flow velocities inside and around the trawl net with catch were 12.41% lower compared with that obtained inside and around the trawl without catch. The turbulent length scale and turbulent Reynolds number obtained in the different part of the trawl net with catch were about 33.05% greater than those obtained on the trawl net without catch, confirming that the unsteady turbulent flow developing inside and around the midwater trawl is influence by the catch and liner. It is observed that the motions of both the trawl without catch and the trawl with catch are mainly of a low-frequency activity and another component related to unsteady turbulent flow street. A complex fluid–structure interaction is then demonstrated where the fluttering motions of the trawl net affect the fluid flow inside and around trawl net, the fluid force, turbulent pattern, and simultaneously, the periodic unsteady turbulent flow influence the trawl motions.

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PIV measurements combined with the motion tracking technique to analyze flow around a moving porous structure

Cited by 14 publications

References 22 publications

Phase-averaged mean properties of turbulent flow developing around a fluttering sheet of net

Phase-averaged mean properties of turbulent flow developing around a fluttering sheet of net

Analysis of hydrodynamics of a moving trawl codend and its fluttering motions in flume tank

Turbulent flow interacting with flexible trawl net structure including simulation catch in flume tank

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