Vortical flow patterns by the cooperative effect of convective and conductive heat transfers in particle-dispersed natural convection

Gu, Jingchen; Takeuchi, Shintaro; Fukada, Toshiaki et al.

International Journal of Heat and Mass Transfer, 2019, 130, 946-959

Number of Access:813（2025-08-15 01:10 Counts）

Identifier to cite or link to this item: https://hdl.handle.net/11094/79017

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Title
Vortical flow patterns by the cooperative effect of convective and conductive heat transfers in particle-dispersed natural convection
Creator
CreatorName
Gu, Jingchen
NRID
1000050372628 1000050372628
ORCID
0000-0003-0091-4542 0000-0003-0091-4542
researchmap permalink
50372628 50372628
Scopus Author ID
35474283000 35474283000
CreatorName
Takeuchi, Shintaro
NRID
1000030812127 1000030812127
CreatorName
Fukada, Toshiaki
NRID
1000030185772 1000030185772
CreatorName
Kajishima, Takeo
Subject
Dense particle-laden flow
Vortical structure
Inhomogeneous media
Heat transfer
Conduction
Convection
Abstract
Cooperative effect of the conductive and convective heat fluxes on the development of vortical structures is studied in a particle-dispersed natural convection. A numerical approach is proposed that visualizes the heat transfer paths through the fluid and finite-volume particles (i.e., non-point particles) to show the spatial extension of the heat fluxes and its influence on the flow field. The approach is applied to a weakly-convective dense particulate system under the Rayleigh number containing more than 4000 particles (solid volume fraction 42.8%) of various conductivities. With highly-conductive particles (in comparison to the ambient fluid), local downward convection of a large-scale vortical flow strengthens the conductive heat flux near the bottom hot wall in the counter-convective direction by the increase of the vertical temperature gradient, and the observation of the spatial extension of the heat flux lines indicates that the increase of the solid volume fraction near the hot wall further strengthens the conductive heat flux. The paired upward convection causes strengthened conductive heat flux near the top cold wall by the same increase mechanism. The above interplay of the local heat fluxes in the dense solid-dispersed media are found to influence on the formation and transition of the large-scale vortical structures through the distribution of the moment of buoyancy in a horizontal plane. An analytical model for a low-dimensional vortex system shows that buoyancy gradient and vorticity diffusion could determine the time-development of the large-scale vortical structure.
Publisher
Elsevier
Source Title
International Journal of Heat and Mass Transfer
Volume (Issue)
130
Page
946-959
Date of Issued
2019-03
Language
English
Handle URL
https://hdl.handle.net/11094/79017
PISSN
00179310
NCID
AA00680396
Relation.isVersionOf
DOI (Publisher Version)
https://doi.org/10.1016/j.ijheatmasstransfer.2018.10.138
Access Rights
open access
CopyRight
© 2018 Elsevier Ltd. This manuscript version is made available under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International license.
oaire:version
Accepted Manuscript
Category
学術雑誌論文 Journal Article