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Building Simulation 2016, 9(6): 677-687 https://doi.org/10.1007/s12273-016-0296-1
Research Article | Issue | Published: 20 May 2016

Numerical investigation of the unsteady flow characteristics of human body thermal plume

Show Author's Information Yulong Liu1,  Yijia Zhao1,  Zhengxian Liu1,2( ),  Jisheng Luo1
School of Mechanical Engineering, Tianjin University, Tianjin 300072, China
State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
Keywords:
numerical simulation, natural convection, human thermal plume, buoyancy, modified turbulence viscosity
Cite this article:
Liu Y, Zhao Y, Liu Z, et al. Numerical investigation of the unsteady flow characteristics of human body thermal plume. Building Simulation, 2016, 9(6): 677-687. https://doi.org/10.1007/s12273-016-0296-1
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Abstract Full text About this article

Human thermal plume is quite important to the study of airflow organization in the indoor environment, especially in the micro-environment research such as personalized ventilation, infectious disease transmission through air, etc. In order to investigate the unsteady fluctuation of the thermal plume around human body, a series of transient numerical simulations are conducted in this study. Numerical simulation based on 9.7 million grids and 0.02 s time step is performed to obtain the detail quantitative data of flow field. The obvious fluctuation and separation are captured in the upper flow region of human body based on the high resolution grids. The maximum time-averaged velocity of the thermal plume is found to be 0.25 m/s while the maximum fluctuate velocity is about 0.07 m/s. The further analysis of frequency spectrum shows that the thermal plume around the body is mainly dominated by the low frequency fluctuation which is lower than 1 Hz and the principal frequency is around 0.1 Hz. In order to overcome the drawback of the high computation cost for application of the engineering simulation, a new numerical simulation method combining a modified k-ε turbulence model and coarse grids is presented. This modified k-ε model can reduce the calculation error of Reynolds stress in the flow region of natural convection through redefining the turbulence viscosity coefficient segmentally and avoid a high numerical viscosity appeared due to the central difference scheme. It can reasonably predict the general fluctuation velocity and the frequency distribution during simulation process in coarse grids and show a huge potential to be applied to the engineering application.


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About this article

Numerical investigation of the unsteady flow characteristics of human body thermal plume

Show Author's information Yulong Liu1, Yijia Zhao1, Zhengxian Liu1,2( ), Jisheng Luo1
School of Mechanical Engineering, Tianjin University, Tianjin 300072, China
State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China

Abstract

Human thermal plume is quite important to the study of airflow organization in the indoor environment, especially in the micro-environment research such as personalized ventilation, infectious disease transmission through air, etc. In order to investigate the unsteady fluctuation of the thermal plume around human body, a series of transient numerical simulations are conducted in this study. Numerical simulation based on 9.7 million grids and 0.02 s time step is performed to obtain the detail quantitative data of flow field. The obvious fluctuation and separation are captured in the upper flow region of human body based on the high resolution grids. The maximum time-averaged velocity of the thermal plume is found to be 0.25 m/s while the maximum fluctuate velocity is about 0.07 m/s. The further analysis of frequency spectrum shows that the thermal plume around the body is mainly dominated by the low frequency fluctuation which is lower than 1 Hz and the principal frequency is around 0.1 Hz. In order to overcome the drawback of the high computation cost for application of the engineering simulation, a new numerical simulation method combining a modified k-ε turbulence model and coarse grids is presented. This modified k-ε model can reduce the calculation error of Reynolds stress in the flow region of natural convection through redefining the turbulence viscosity coefficient segmentally and avoid a high numerical viscosity appeared due to the central difference scheme. It can reasonably predict the general fluctuation velocity and the frequency distribution during simulation process in coarse grids and show a huge potential to be applied to the engineering application.

Keywords: numerical simulation, natural convection, human thermal plume, buoyancy, modified turbulence viscosity

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Publication history
Copyright
Acknowledgements

Publication history

Received: 25 January 2016
Revised: 07 April 2016
Accepted: 28 April 2016
Published: 20 May 2016
Issue date: December 2016

Copyright

© Tsinghua University Press and Springer-Verlag Berlin Heidelberg 2016

Acknowledgements

This work is supported by the National Basic Research Program of China ("973" project of China, Grant No. 2012CB720101) and the National Natural Science Foundation of China (Grant No. 51276125).

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