Boundary Condition Development For Efficient And Accurate Ground Thermal Modelling For Long-Term Climate Change Effects
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Authors
Alavi, Amirali
Date
2025-10-03
Type
thesis
Language
eng
Keyword
Permafrost , Climate change , Numerical model , Bottom boundary condition , Heat flux
Alternative Title
Abstract
Permafrost-rich terrains, extensively distributed across Arctic and sub-Arctic regions, are increasingly threatened due to both anthropogenic disturbances and ongoing climate change. Human activities, particularly the development of infrastructure, are reshaping the thermal regime of these sensitive areas. In parallel, climate warming has intensified over recent decades, with the most pronounced impacts observed in high-altitude regions. Prediction of the permafrost thermal state over the long-term is critical, and addressing this challenge requires the use of numerical modeling tools capable of simulating permafrost responses over a range of climatic and environmental conditions. These models serve as digital twins of real-world systems and offer an effective framework for predicting subsurface thermal behavior. However, the reliability of such models is highly sensitive to the accuracy of their input parameters. While several inputs, such as surface temperature and soil properties, are well-characterized, others remain underexplored. One such input is the bottom boundary condition (BBC), a crucial element in finite element modeling of ground thermal regimes. Although recent studies have proposed novel methods for defining BBCs, their applicability across diverse homogeneous and heterogeneous soil profiles with varying thermophysical properties remains uncertain. In this study, numerical modeling confirmed the applicability of a previously proposed variable heat flux BBC method across a broader range of homogeneous and heterogeneous soil profiles. Additionally, a clear linear correlation was observed between the depth-averaged frozen thermal conductivity and the fitting parameters to local heat flux fitted lines, offering a practical relationship that can assist modelers in improving the accuracy of shallow ground thermal simulations. Furthermore, this study identifies the duration over which a shallow model remains valid when a constant heat flux is applied at the base, before the temperature at the bottom boundary begins to diverge from baseline deep model ground temperature, highlighting that even models using constant geothermal flux can reliably capture ground thermal behavior within that timeframe.
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Intellectual Property Guidelines at Queen's University
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This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivatives 4.0 International