Guidelines for heat and moisture modelling in constructions using multiphysics FEM software
van_Schijndel, J.
2008 Building Physics Symposium Leuven, Oct. pp. 59-62
Heat, Moisture, Modeling, Multiphysics, FEM
van_Schijndel, J., (2008), "Guidelines for heat and moisture modelling in constructions using multiphysics FEM software", Building Physics Symposium Leuven, Oct. pp. 59-62.
Abstract:
Multiphysics treats simulations that involve multiple physical models or multiple simultaneous physical phenomena mostly using the Finite Element Method (FEM). The commercially available software packages like ANSYS Multiphysics, LS-DYNA, COMSOL Multiphysics, and FlexPDE are very promising for application in the area of building physics. However, using these Multiphysics tools for modeling heat and moisture transport in constructions, one might encounter numerical problems. Especially the multi-layered mixed moisture transport (i.e. vapour and water) part can be tricky to solve. Amongst other possibilities, the multiphysics modeling approach of van Schijndel (2007) is selected. A guideline on how to implement up to 3D heat air and moisture (HAM) transport models using COMSOL (2008) is already provided (van Schijndel 2006). Another recent development concerning COMSOL is presented in Tariku et al. (2008). This work shows a successful implementation of 1D HAM transport using relative humidity as moisture potential. This paper presents two major extensions to work of van Schijndel (2006) and Tariku et al. (2008), described in the following sections: First, the implementation of LPc as moisture potential for including both vapour and liquid transport and second, the implementation of material and boundary functions for calculating the PDE coefficients from the material properties. The implementation of the two new extensions is verified using the HAMStad benchmark 1 (Hagentoft et al 2002).
(* The underscore in the author's name is due to deficiency in the programming.)
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