Electrowetting on dielectric
Electrowetting on dielectric (EWOD)

This is the documentation of the EWOD code submitted to Archive on Numerical Software.

The purpose of this code is to simulate electrowetting on dielectric, which consists in the local modification of the surface tension betweent two immiscible fluids via electric actuation. This phenomenon has several practical applications, therefore it is important to possess simulation tools that are simple yet accurate. The following figure shows a prototype of an electrowetting device:

Schematics of an electrowetting device

The solid black stripes represent two conducting plates, which entrap a two-phase immiscible fluid. Voltage is applied to the plates and this generates an electric field between them. The generated electric field changes the properties of the fluids, and thus they can be manipulated.

Unlike many of the problems usually tackled by scientific computing, the governing laws for this phenomenon are still open for debate. Very little is known about what happens at the interface between the two fluids and the solid container. The purpose of this code is to explore the possiblities of a model of electrowetting, which consists of a Cahn Hilliard Navier Stokes system of equations, coupled with a convection diffusion equation that models the transport of charges and a Poisson equation to model the voltage. The fluid and charge equations are posed in the fluid domain, whereas the voltage equation in the fluid and plates.

Due to the intricate coupling of the equations, as well as its high number, the structuring of the code becomes of importance. The main contributions of this work are the AsFunction and Problem class templates. AsFunction is our attempt at encapsulating the information relevant to a problem and allowing it to interface with another system, where it can serve as input. Problem, as its name indicates, is the way we abstract the common features of a problem.

In addition, we have "application specific" classes: DataStorage, GLPotential, InterfaceEnergy, material_function, Material_Parameters, Phase0 and Vbc. These are nothing but classes that represent specific objects in our system of equations: Coefficients, initial and/or boundary conditions, etc.

Finally, the classes that represent each one of the physical processes are: CahnHilliard, Charge, Pressure, Voltage and Velocity. The class CHNSE refers to a fixed point iteration scheme used to solve the fluid problem. The main class, i.e. the one that dirvies all these processes and keeps them in sync is EWOD.

Abner J. Salgado.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.