Numerical analysis of coupled thermo - hydraulic problems in 1 geotechnical engineering

Abstract

10 Ground sources energy systems, such as open-loop systems, have been widely employed in recent 11 years due to their economic and environmental benefits compared to conventional heating and cooling 12 systems. Numerical modelling of such geothermal system requires solving a coupled thermo13 hydraulic problem which is characterised by a convection-dominated heat transfer which can be 14 challenging for the Galerkin finite element method (GFEM). This paper first presents the coupled 15 thermo-hydraulic governing formulation as well as the coupled thermo-hydraulic boundary condition, 16 which can be implemented into a finite element software. Subsequently, the stability condition of the 17 adopted time marching scheme for coupled thermo-hydraulic analysis is established analytically. The 18 behaviour of highly convective problems is then investigated via a series of analyses where 19 convective heat transfer along a soil bar is simulated, with recommendations on the choice of an 20 adequate discretisation with different boundary conditions being provided to avoid oscillatory 21 solutions. Finally, the conclusions from the analytical and numerical studies are applied to the 22 simulation of a boundary value problem involving an open-loop system, with the results showing 23 good agreement with an approximate solution. The main objective of this paper is to demonstrate that 24 the GFEM is capable of dealing with highly convective geotechnical problems. 25

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Cite this paper

@inproceedings{Cui2016NumericalAO, title={Numerical analysis of coupled thermo - hydraulic problems in 1 geotechnical engineering}, author={W. P. Cui and K. A. Gawecka}, year={2016} }