Ricerc@Sapienza

Computer simulations of fluids at the microscale have been thoroughly used in the field of microfluidics for interpretation of experimental observations and for the design of new devices. One of the most used simulation technique is Molecular Dynamics (MD), as it models explicitly every atom of the system, allowing the simulation at nanoscale of complex systems such as biological channels or nanofluidic devices for energy harvesting. The drawback of MD is its computational cost, which makes unfeasible to use it to simulate complete microfluidic devices. At larger scales, continuum computational fluid dynamics techniques are commonly employed. In this case, the main drawback is associated to the lack of thermal fluctuations, which are crucial for correct modelling of several transport phenomena. In fact, most microfluidic systems are mesoscale systems, meaning that some features of the microscopic world as the discrete nature of matter and density fluctuations may be neglected, while other features as thermal motion and the finiteness of the Debye layer can't be neglected. To simulate these systems, coarse grained techniques which drop many unnecessary degrees of freedom, retaining only the relevant features of the system are needed.
The aim of this project is to develop and validate a coarse grained approach able to model the thermal fluctuations, the presence of solid particles immersed in the solution (fluid-structure interactions), the presence of coupled electric and fluid dynamics phenomena (i.e. electrohydrodynamics). The model will be developed in the framework of Dissipative Particle Dynamics (DPD), a mesoscale technique used to model microscale flow. Our main contribution will be to expand it to include ionic fluxes and electric polarization. This expansion will allow to use DPD for a broader class of technologically relevant problems, such as nanopore sensing or energy harversting from a salt gradient.