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http://dx.doi.org/10.6112/kscfe.2016.21.4.001

ANALYSIS OF TURBULENT BOUNDARY LAYER OF NATURAL CONVECTION CAUSED BY FIRE ALONG VERTICAL WALL  

Jang, Yong-Jun (Railroad Safety and Certification Center, Korea Railroad Research Institute)
Kim, Jin-Ho (Smart Station Research Team, Korea Railroad Research Institute)
Ryu, Ji-Min (Railroad Safety and Certification Center, Korea Railroad Research Institute)
Publication Information
Journal of computational fluids engineering / v.21, no.4, 2016 , pp. 1-10 More about this Journal
Abstract
The analysis of characteristics of turbulent flow and thermal boundary layer for natural convection caused by fire along vertical wall is performed. The 4m-high vertical copper plate is heated and kept at a uniform surface temperature of $60^{\circ}C$ and the surrounding fluid (air) is kept at $16.5^{\circ}C$. The flow and temperature is solved by large eddy simulation(LES) of FDS code(Ver.6), in which the viscous-sublayer flow is calculated by Werner-Wengle wall function. The whole analyzed domain is assumed as turbulent region to apply wall function even through the laminar flow is transient to the turbulent flow between $10^9$<$Gr_z$<$10^{10}$ in experiments. The various grids from $7{\times}7{\times}128$ to $18{\times}18{\times}128$ are applied to investigate the sensitivity of wall function to $x^+$ value in LES simulation. The mean velocity and temperature profiles in the turbulent boundary layer are compared with experimental data by Tsuji & Nagano and the results from other LES simulation in which the viscous-sublayer flow is directly solved with many grids. The relationship between heat transfer rate($Nu_z$) and $Gr_zPr$ is investigated and calculated heat transfer rates are compared with theoretical equation and experimental data.
Keywords
Turbulent boundary layer; Natural convection; Large Eddy Simulation; Wall function; FDS(Fire Dynamics Simulator;
Citations & Related Records
Times Cited By KSCI : 2  (Citation Analysis)
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