Abstract: A self-adaptive precise algorithm in the time domain was employed to solve 2-D nonlinear coupled heat and moisture transfer problems. By expanding variables at a discretized time interval, the variations of variables can be described more precisely, and a nonlinear coupled initial and boundary value problem was converted into a series of recurrent linear boundary value problems which are solved by FE technique. In the computation, no additional assumption and the nonlinear iteration are required, and a criterion for self-adaptive computation is proposed to maintain sufficient computing accuracy for the change sizes of time steps. In the numerical comparison, the variations of material properties with temperature,moisture content, and both temperature and moisture content are taken into account, respectively. Satisfactory results have been obtained, indicating that the proposed approach is capable of dealing with complex nonlinear problems.

Key words: finite element, nonlinear transfer problem, time stepping, self-adaptive computation