Overview

Overview

HyDro is a simulation software for the wetting phenomena of liquid droplets on solid surface, devoloped by National Institute of Advanced Industrial Science and Technology (AIST). It simulates the shape of droplet placed on hydrophilic/hydrophobic patterns effectively and accurately by our original algorithm, Hybrid Energy Minimization (HEM) method.

When a small droplet is put on a homogeneous solid surface, the droplet will take the form of a partial sphere. The angle between the substrate surface and the liquid surface is called contact angle, which is a parameter determined by the properties of solid surface and liquid. The contact angle is small on hydrophilic surfaces, and is large on hydrophobic surfaces. Here the homogeneous means the surface with a constant contact angle.

However, it is generally difficult to guess the shape of droplet put on a heterogeneous solid surface. In order to simulate the droplet shape effectively on a computer, we developed our original software: HyDro.

The calculation of HyDro is based on the energy-minimization principle, that is, an equilibrium droplet should be in the state with the minimum energy. The users first define the shape of domains on the substrate surface, and set contact angles for each domain. Then, they create an initial shape of droplet (e.g. sphere), and start the energy-minimization calculation. During the calculation, the program evolves the shape of droplet gradually so that the total energy decreases. Finally the droplet reaches to a minimum-energy state, and the calculation is stopped. (This program cannot calculate the time-evolution of the droplet.) The users can watch the calculation processes and results in a 3D view, and export the results in several formats.