ABSTRACT
Spontaneous liquid flow originated purely by capillary pressure (interfacial tension effects) is called wicking flow. There are different kinds of wicking, as specified in Ref. 60. The simplest case is the spontaneous flow into a capillary. The practical importance of this is having wicking flows into porous media. Microlevel flows related to LCM processes are one of many such examples. Direction of the wicking flow is not restricted. When it is in the vertical direction, it is opposed by gravitational effects. However, capillary action can be so strong that gravity can be neglected. Wicking flow into a single capillary is different than flow into a porous medium. In the latter case, the flow front is not macroscopically sharp and if the fluid source is removed, wicking continues until an equilibrium state is reached. This is in contradiction with the former case, where the motion immediately stops [66].
