ABSTRACT
At a very low rate of penetration (curves 1 and 2), the concentration Cm does not differ appreciably from C0 due to the small Peclet number (Pe=vl/ D) and predominance of diffusion. At very high values of K, the concentration close to the meniscus tends to zero. This also takes place in the case of forced penetration under the action of an external pressure [19], when Pe>>1. In this case, surfactant molecules cannot reach the meniscus and influence the contact angle. The effect of capillary radius is similar: the smaller the values of r, the more pronounced is the influence of surfactant adsorption. An increase in Ds2 values leads to some decrease in Cm due to the enhanced diffusion along the nonwetted capillary surface.
