Imperial College London
Portrait Picture

ProfessorSylvainLaizet

Faculty of Engineering, Department of Aeronautics

Professor in Computational Fluid Mechanics
 
 
 
//

Contact

 

+44 (0)20 7594 5045s.laizet Website

 
 
//

Location

 

339City and Guilds BuildingSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{Khojasteh:2021:10.1063/5.0060644,
author = {Khojasteh, AR and Yang, Y and Heitz, D and Laizet, S},
doi = {10.1063/5.0060644},
journal = {Physics of Fluids},
pages = {1--13},
title = {Lagrangian coherent track initialisation},
url = {http://dx.doi.org/10.1063/5.0060644},
volume = {33},
year = {2021}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Advances in time-resolved three-dimensional Particle Tracking Velocimetry (4D-PTV)techniques have been consistently revealed more accurate Lagrangian particle motions.A novel track initialisation technique as a complementary part of 4D-PTV, based on localtemporal and spatial coherency of neighbour trajectories, is proposed. The proposed Lagrangian Coherent Track Initialisation (LCTI) applies physics-based Finite Time LyapunovExponent (FTLE) to build four frame coherent tracks. We locally determine LagrangianCoherent Structures (LCS) among neighbour trajectories by using the FTLE boundaries(i.e., ridges) to distinguish clusters of coherent motions. To evaluate the proposed technique, we created an open-access synthetic Lagrangian and Eulerian dataset of the wakedownstream of a smooth cylinder at a Reynolds number equal to 3900 obtained fromthree-dimensional (3D) Direct Numerical Simulation (DNS). Performance of the proposedmethod based on three characteristic parameters, temporal scale, particle concentration(i.e., density), and noise ratio, showed robust behaviour in finding true tracks compared tothe recent initialisation algorithms. Sensitivity of LCTI to the number of untracked andwrong tracks are also discussed. We address the capability of using the proposed methodas a function of a 4D-PTV scheme in the Lagrangian Particle Tracking (LPT) challenge.We showed that LCTI prevents 4D-PTV divergence in flows with high particle concentrations. Finally, the LCTI behaviour was demonstrated in a jet impingement experiment.LCTI was found to be a reliable tracking tool in complex flow motions, with a strengthrevealed for flows with high velocity and acceleration gradients.
AU  - Khojasteh,AR
AU  - Yang,Y
AU  - Heitz,D
AU  - Laizet,S
DO  - 10.1063/5.0060644
EP  - 13
PY  - 2021///
SN  - 1070-6631
SP  - 1
TI  - Lagrangian coherent track initialisation
T2  - Physics of Fluids
UR  - http://dx.doi.org/10.1063/5.0060644
UR  - https://aip.scitation.org/doi/10.1063/5.0060644
UR  - http://hdl.handle.net/10044/1/91522
VL  - 33
ER  -
Download