Models for drug delivery are based on the use of stirred tanks to represent organs that contain no mass transfer resistances. In the original Krogh cylinder model, a mass transfer resistance shows up but there is no convection in the tissue where convection should matter. In the present study, a two-dimensional flow field is used to show that when a liquid enters the capillary, some leave through the walls into the tissue at the arterial end and then doubles back into the capillary at the venous end. Some flow does not return which is taken to be the flow to the lymphatic system. We can get the measured transcapillary pressure drop of about 2,666 Pa if in addition the compliance of the tube wall is taken into account. Very realistic flow fields have been shown for a model liver and a tumor.

A model for the dynamic contact angles and the spreading kinetics of nematic liquid crystals on a solid surface is presented for the first time using the continuum theory of liquid crystals. The equations of motion for this system are integrated for a wedge or a drop that is thin and moves slowly. The dynamic contact angle is found to depend on the capillary number that represents the importance of viscocapillarity and on the elasticity number that is the ratio between the elastic and surface forces. The model provides an explanation for the extra volume dependence that is reported in experiments, as well as one case of recoil, and for the observation that very small drops were reported to be immobile. For the first time, these previous experimental observations are shown to be due to elastic effects.

A distributed system called a Krogh cylinder is used here to quantify the transport of a solute from the capillary into the extravascular tissue. The capillary network is broken down into cylindrical cells, each containing a capillary and an appropriate amount of extravascular tissue. The flow in the cylinder model has two-dimensional velocities, which are in the axial and radial directions. All parameters of the system, together with the geometric ones, have been

Brine is used to displace crude oil in a reservoir and its performance improves when brine contains nanoparticles. It is the presence of nanoparticles in confinements, such as at dynamic contact lines and in thin films, which is of importance. The investigators here have determined a fast way to obtain confined systems by evaporating a small drop of water containing nanoparticles. Water droplets containing nanoparticles of alumina or silica were evaporated on surfaces of polyethylene terephthalate sheets, which are partially wet by water, and glass which is fully wet. After the liquid in the drops evaporated, the residues were examined under a microscope and sintering and melting effects, crystals growth and dendritic formations for alumina and monoliths for silica were seen. The coffee stains are seen in most cases; however measurements show that the contact lines are not always pinned. Turbidity measurements showed that no significant reformation could have taken place in the bulk liquid. A simple model for evaporation, based on geometric measurements, showed that much of the film seen on the solid arose out of evaporation of water that forced the particles down. Sintering rates into the interior could be quantified and shown to be unstable.