Liquid Drop Weight and Shape Method

In many processes (such as oil recovery, blood flow, underground water), one encounters liquid flow through thin (micrometer diameter), noncircular-shaped tubes, or pores. In the literature, one finds studies that address these latter systems. In another context of liquid drop formation, for example, in an inkjet nozzle, this technique falls under a class of scientifically challenging technology. The inkjet printer demands such quality that this branch of drop-on-demand technology is much in the realm of industrial research. All combustion engines are controlled by oil drop formation and evaporation characteristics. The important role of capillary forces is obvious in such systems. 

A simple method is to count the number of drops (e.g., 10 or more) and measure the weight. 

A more convenient method may be used, in which a fluid is pumped and the drops are collected and weighed. Since in some systems (solutions) there may be kinetic effects, care must be taken to keep the flow as slow as possible. This system is very useful in studying what one finds in daily life phenomena oil flow, blood cells flowing through arteries, etc. In those cases where the volume of fluid available is limited, this method may be used with advantage. By decreasing the diameter of the tubing, one can work with fluids less than 1 mL. This may be the case for systems such as eye fluids, etc. 

The magnitude of y can be determined from either the maximum weight or the shape of the drop. 

Maximum weight method The detachment method is based upon the following to detach a body from the surface of a liquid that wets the body, it is necessary to overcome the same surface tension forces that operate when a drop is broken away. The liquid attached to the solid surface on detachment creates the following surfaces  

---