Comparing Different Approaches for Moisture Transfer Inside Constructions with Air Gaps

L. Nespoli[1], M. Bianchi Janetti[2], F. Ochs[2]
[1]Politecnico di Milano, Milan, Italy
[2]University of Innsbruck, Innsbruck, Austria

A model for the conjugate simulation of heat and moisture transfer inside porous materials and fluid domains is implemented in COMSOL Multiphysics®. The results of this model are compared with those obtained through a simplified approach: the line-source approach. The models are both validated with experimental data and with numerical results from other authors. On the one hand the conjugate approach is able to predict better results from a physical point of view, since it calculates the velocity field inside the air cavities through computational fluid dynamics (CFD); on the other hand, including fluid dynamics in long period hygrotermal simulation increases numerical effort and computational time. Thus the simplified approach can be advantageous e.g. in building physics applications.