Numerical Study of Thermo-hydraulic Boundary Condition for Surface Energy Balance

Hosung Shin; Jae-Hyeung Jeoung

doi:10.7843/kgs.2021.37.12.25

All Issue

2021 Vol.37, Issue 12 Preview Page Next Page

Numerical Study of Thermo-hydraulic Boundary Condition for Surface Energy Balance 지표면 열평형의 열-수리적 경계조건에 대한 수치해석

31 December 2021. pp. 25-31

PDF XML

Abstract

Boundary conditions for thermal-hydraulic problems of soils play an essential role in the numerical accuracy. This study presents a boundary condition considering the thermo-hydraulic interaction between the ground and the atmosphere. Ground surface energy balance consists of solar radiation, ground radiation, wind convection, latent heat from water evaporation, and heat conduction to the ground. Equations for each heat flux are presented, and numerical analyses are performed in conjunction with the FEM program for the thermal-hydraulic phenomenon of unsaturated soils. Numerical results using the weather data at the Ulsan Meteorological Observatory are similar to the measured surface temperature. Latent heat caused by water evaporation during the daytime lowers the surface temperature of the bare soil, and a thermal equilibrium is reached at nighttime when the effect of the ground condition is significantly reduced. The temperature change of the surface ground is diminished at the deeper ground due to its thermal diffusion. Numerical analysis where the surface ground temperature is the primary concern requires considering the thermo-hydraulic interaction between the ground and the atmosphere.

Keywords

FEM

Ground surface energy balance

Thermo-hydraulic boundary condition

지반의 열-수리 현상에 대한 수치해석에서 경계조건은 해석결과의 정확도에 중요한 역할을 한다. 본 연구에서는 지반과 대기의 상호작용을 고려한 열-수리 경계조건을 제시하였다. 지면의 에너지 평형은 태양복사, 지구복사, 바람에 의한 대류, 수분 증발에 대한 잠열 그리고 지중으로의 열전도로 구성된다. 각각의 열흐름에 대한 방정식을 제시하고, 불포화 지반의 열-수리 현상에 대한 해석프로그램과 연계하여 수치해석을 수행하였다. 울산기상대에서 관측된 기상데이터를 이용한 수리-열적 해석에서 실측된 지표면 온도와 수치해석 결과가 매우 유사하였다. 낮시간의 수분 증발에 의한 잠재열은 비포장 지면의 온도를 낮추며, 야간시간에는 지면조건의 영향이 감소한 열적평형 상태에 도달하였다. 지면의 온도변화는 지중으로 깊어질수록 열확산으로 감소하였다. 지표면의 온도가 주요 관심사인 수치해석에서는 지반과 대기의 열-수리적 상호작용을 고려한 수치해석을 수행해야 한다.

References

Aluwihare, S. and Watanabe, K. (2003), "Measurement of Evaporation on Bare Soil and Estimating Surface Resistance", Journal of Environmental Engineering, Vol.129, No.12, pp.1157-1168. 10.1061/(ASCE)0733-9372(2003)129:12(1157)

Asaeda, T. and Ca, V.T. (1993), "The Subsurface Transport of Heat and Moisture and its Effect on the Environment: A Numerical Model", Boundary-Layer Meteorology, Vol.65, pp.159-179. 10.1007/BF00708822

Chen, J., Wang, H., and Xie, P. (2019), "Pavement Temperature Prediction: Theoretical Models and Critical Affecting Factors", Applied Thermal Engineering, Vol.158, 113755. 10.1016/j.applthermaleng.2019.113755

Gray, D.M. (1970), Handbook on the principals of hydrology, Canadian National Committee for the International Hydrological Decade.

Groh, J., Vanderborght, J., Pütz, T., and Vereecken, H. (2016), "How to Control the Lysimeter Bottom Boundary to Investigate the Effect of Climate Change on Soil Processes?", Vadose Zone Journal, Vol.15, 10.2136/vzj2015.08.0113. 10.2136/vzj2015.08.0113

Gui, J.G., Phelan, P.E., Kaloush, K.E., and Golden, J.S. (2007), "Impact of Pavement Thermophysical Properties on Surface Temperatures", Journal of Materials in Civil Engineering, Vol.19, No.8, pp.683-690. 10.1061/(ASCE)0899-1561(2007)19:8(683)

Hwang, S.H. (2017), "A Study on Prediction Method for Low-depth Ground Temperature by Using Surface Energy Balance Equation", Journal of KIAEBS, Vol.11, No.2, pp.142-148.

Kim, H., Kim, Y.T., Min, T.K., Shin, H., and Park, D.K. (2012), "Analysis of Seepage Velocity in Unsaturated Weathered Soils Using Rainfall Infiltration", Journal of the Korean Geotechnical Society, Vol.28, No.2, pp.71-78. 10.7843/kgs.2012.28.2.71

Korea Meteorological Administration. https://data.kma.go.kr

Qin, Y. and Hiller, J.E. (2014), "Understanding Pavement-surface Energy Balance and its Implications on Cool Pavement Development", Energy Buildings, Vol.85, pp.389-399. 10.1016/j.enbuild.2014.09.076

Sedighi, M., Hepburn, B.D.P., Thomas, H.R., and Vardon, P.J. (2018), "Energy Balance at the Soil Atmospheric Interface", Environmental Geotechnics, Vol.5, No.3, pp.46-157. 10.1680/jenge.15.00054

Shin, H. (2011), "Formulation of Fully Coupled THM behavior in Unsaturated Soil", Journal of the Korean Geotechnical Society, Vol.27, No.3, pp.75-83. 10.7843/kgs.2011.27.3.075

Tan, S.A. and Fwa, T.F. (1992), "Influence of Pavement Materials on the Thermal Environment of Outdoor Spaces", Building and Environment, Vol.27, No.3, pp.289-295. 10.1016/0360-1323(92)90030-S

van de Griend, A.A. and Owe, M. (1994), "Bare Soil Surface Resistance to Evaporation by Vapor Diffusion under Semiarid Conditions", Water Resour. Res., Vol.30, No.2, pp.181-188 10.1029/93WR02747

Yilmaz, H., Toy, S., Irmak, M.A., Yilmaz, S., and Bulut, Y. (2008), "Determination of Temperature Differences between Asphalt Concrete, Soil and Grass Surfaces of the City of Erzurum, Turkey", Atmósfera, Vol.21, No.2, pp.135-146.

Yu-Shan, A. and Shakiba, M. (2021), "Flooded Pavement: Numerical Investigation of Saturation Effects on Asphalt Pavement Structures", Journal of Transportation Engineering, Part B: Pavements, Vol.147, No.3, 04021025. 10.1061/JPEODX.0000276

Zhao, Y., Jiang, J., Dai, Y., Zhou, L., and Ni, F. (2020), "Thermal Property Evaluation of Porous Asphalt Concrete based on Heterogeneous Meso-structure Finite Element Simulation", Applied Sciences, Vol.10, No.5, 1671. 10.3390/app10051671

Information

Publisher :The Korean Geotechnical Society
Publisher(Ko) :한국지반공학회
Journal Title :Journal of the Korean Geotechnical Society
Journal Title(Ko) :한국지반공학회 논문집
Volume : 37
No :12
Pages :25-31
Received Date : 2021-11-05
Revised Date : 2021-11-24
Accepted Date : 2021-11-24
DOI :https://doi.org/10.7843/kgs.2021.37.12.25

Journal of the Korean Geotechnical Society ISSN:1229-2427(Print) 2288-646X(Online) 한국지반공학회 논문집

All Issue