Numerical Simulation of Moisture Transmission Through a Fiber Assembly

Abstract

In this paper, we attempt to numerically simulate moisture transmission phenomena in a fiber assembly. Moisture distribution is calculated with the help of a two-dimensional model consisting of two rectangular areas occupied by fibrous material and air space. Changes in the moisture concentration distribution with time and in the absorption rate from the air space into the fibrous material are then discussed in terms of various diffusion constants of the fibrous materials and the model dimensions. Transient phenomena of moisture transmission with time are clarified by different diffusion constants of the fibrous material. In the air space, the slope of the curve of the mean concentration change with time is initially steeper for a smaller diffusion constant of the fibers than for a larger diffusion constant. With increasing time, the tendency reverses and the curves intersect each other. The effects of the ratio of model thickness to width on moisture transmission are also discussed. For a narrower model, the time required to attain equilibrium concen tration is longer because of the narrow air space entrance. With increasing model width, the time quickly becomes short. But for even wider models, the time required again increases a little because of the larger entrance area of the fibrous material.