This work describes an iterative technique for the definition of condensation across two-dimensional elements via the boundary element method (BEM). Initially, the BEM is used to calculate the steady-state conduction of heat and vapour diffusion, discretizing only the boundary materials' discontinuities. Then, a small sub-domain is defined, where condensation develops; that is, where the vapour pressure exceeds the vapour saturation pressure. Using the Glaser approach, the vapour pressure is equalised to the vapour saturation pressure, and then the vapour equilibrium is redefined by means of the BEM solution. This process is repeated until all sub-domains where vapour pressure exceeds vapour saturation pressure are eliminated.

The method is first implemented and validated by applying it to a simple one-dimensional hygrothermal problem, for which the solution is calculated analytically. The applicability of the proposed method is then illustrated by computing the two-dimensional condensation across a T shaped element, for different boundary conditions.

• condensation and evaporation
• HAM: simplified models - simplification
• mathematics: numerical method, finite difference, finite element

1. Steady-state moisture diffusion in curved walls, in the absence of condensate flow, via the BEM: a practical Civil Engineering approach (Glaser method)