The paper of the month, chosen by the Editor-in-Chief, is "Investigation of the Teapot Effect" by Ali Kibar;  

DOI: 10.12693/APhysPolA.144.26

Physics is not only about abstract things or exotic materials, physics helps to understand every-day effects as well. Some of such effects can easily be explained, some others are rather hard. Spilling liquid from a teapot is one of such hard everyday effects. It is generally known that sometimes the liquid flowing out of a spout adheres to the outer part of it instead of flowing directly downwards. This is the teapot effect discussed in the paper.

The effect is not easy to explain since many factors contribute to the behavior of the liquid flowing out of a spout. Liquid viscosity, capillary adhesive force, ambient pressure are among the most important factors that determine the character of the flow.

All relevant hydrodynamic effects are considered in this paper. Physical analysis led to hydrodynamic equations that were solved numerically on a huge mesh. The results are illustrated by experiments with liquids flowing out of teapots having spouts covered by hydrophobic and hydrophilic surfaces. I enjoyed the experimental part of the paper – photographs of a liquid pouring out of a teapot illustrate well many aspects of effects taking place.

I strongly recommend reading this paper, I enjoyed the application of advanced physical methods to discuss an every-day effect.

The Editor-in-Chief