TY - GEN
T1 - Experimental analysis of lagrangian coherent structures and chaotic mixing in Rayleigh-Benard convection
AU - Watanabe, Masahito
AU - Kitamura, Yusuke
AU - Hatta, Naoki
AU - Yoshimura, Hiroaki
N1 - Funding Information:
HY is partially supported by JSPS Grant-in-Aid for Scientific Research (17H01097), Waseda University (SR 2019C-176, SR 2019Q-020, SR 2020C-194), JST CREST (JPMJCR1914), MEXT “Top Global University Project”, and MW is supported by Waseda Research Institute for Science and Engineering ‘Early Bird - Young Scientists’ community.
Funding Information:
HY is partially supported by JSPS Grant-in-Aid for Scientific Research (17H01097), Waseda University (SR 2019C-176, SR 2019Q-020, SR 2020C-194), JST CREST (JPMJCR1914), MEXT ?Top Global University Project?, and MW is supported by Waseda Research Institute for Science and Engineering ?Early Bird - Young Scientists? community.
Publisher Copyright:
Copyright © 2020 ASME
PY - 2020
Y1 - 2020
N2 - It is known that some fluid particles may be transported chaotically in Lagrangian description although the velocity field seems to be stable in Eulerian description. A typical example can be found in the system of two-dimensional Rayleigh-Benard convection with perturbed velocity fields, which has been investigated as a low dimensional mechanical model of fluid phenomena associated with natural convection in order to clarify the mechanism of fluid transport (see, for instance, [2]). In this study, we make an experimental study on the global structures of chaotic mixing appeared in the two-dimensional perturbed Rayleigh-Benard convection by analyzing Lagrangian coherent structures (LCSs), which correspond to the invariant manifolds of time-dependent mechanical systems. We develop an apparatus to measure the velocity field by Particle Image Velocimetry (PIV) and then show the LCSs which can be numerically detected from the experimental data by computing Finite-time Lyapunov exponent (FTLE) fields. Finally, we show the global structures of chaotic mixing appeared in the perturbed Rayleigh-Benard convection as well as the steady convection by experiments. In particular, we clarify how the LCSs are entangled with each other around the cell boundaries to carry out chaotic Lagrangian transports.
AB - It is known that some fluid particles may be transported chaotically in Lagrangian description although the velocity field seems to be stable in Eulerian description. A typical example can be found in the system of two-dimensional Rayleigh-Benard convection with perturbed velocity fields, which has been investigated as a low dimensional mechanical model of fluid phenomena associated with natural convection in order to clarify the mechanism of fluid transport (see, for instance, [2]). In this study, we make an experimental study on the global structures of chaotic mixing appeared in the two-dimensional perturbed Rayleigh-Benard convection by analyzing Lagrangian coherent structures (LCSs), which correspond to the invariant manifolds of time-dependent mechanical systems. We develop an apparatus to measure the velocity field by Particle Image Velocimetry (PIV) and then show the LCSs which can be numerically detected from the experimental data by computing Finite-time Lyapunov exponent (FTLE) fields. Finally, we show the global structures of chaotic mixing appeared in the perturbed Rayleigh-Benard convection as well as the steady convection by experiments. In particular, we clarify how the LCSs are entangled with each other around the cell boundaries to carry out chaotic Lagrangian transports.
KW - Chaotic mixing
KW - Lagrangian coherent structure
KW - Lobe dynamics
KW - Rayleigh-Benard convection
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U2 - 10.1115/FEDSM2020-20116
DO - 10.1115/FEDSM2020-20116
M3 - Conference contribution
AN - SCOPUS:85094115993
T3 - American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM
BT - Fluid Applications and Systems; Fluid Measurement and Instrumentation
PB - American Society of Mechanical Engineers (ASME)
T2 - ASME 2020 Fluids Engineering Division Summer Meeting, FEDSM 2020, collocated with the ASME 2020 Heat Transfer Summer Conference and the ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels
Y2 - 13 July 2020 through 15 July 2020
ER -