Interface pinning in spontaneous imbibition - art. no. 051605

Evaporation and gravity induced pinning in spontaneous imbibition are exami ned within a phase field formalism. Evaporation is introduced via a noncons erving, term and gravity through a convective term that constrains the infl ux of liquid. Their effects are described by dimensionless coupling constan ts epsilon and g, respectively. From liquid conservation, the early time be havior of the average interface position follows H(t)similar tot(1/2) until a crossover time t*(g, epsilon). After that the pinning height H-p(g,epsil on) is approached exponentially in time, in accordance with mean field theo ry. The statistical roughness of the interface is described by an exponent chi similar or equal to 1.25 at all stages of the rise, but the dynamic len gth scale controlling roughness crosses over from xi (x)similar toH(1/2) to a time independent pinning length scale xi (p)(epsilon ,g).