A model of coupled liquid moisture and heat transfer in porous textiles with consideration of gravity

A mathematical model for simulating flow fields in porous textiles with consideration of gravity is described in this article. The article focuses on the analysis of the physical model of liquid diffusion in porous textiles. The model assumes that the liquid water moves in the composite network of capillaries of the porous textile and is carried to the surface by capillary action. The analysis includes the capillary action with phase change and the gravity effects of the liquid water. The balance between capillary and gravity forces is measured by a dimensionless number (named GS number), N=3epsilon(l)rho(l)d(c)gL/2sigma cos phiepsilon, which describes the ratio of gravity to surface tension force in porous textiles. On the basis of a fractional volume-of fluid (VOF) method, the distributions of the temperature, moisture concentration, and liquid water content in the porous textiles the different degrees of hygroscopicity were computed numerically by this technique. The numerical solutions indicate that this model is satisfactory.