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Atomistic methods

Hybrid atomistic-continuum (HAC) modeling of liquids

In the HAC method, the liquid is simulated using the Navier-Stokes (NS) equations and Molecular Dynamics (MD) simultaneously. This is carried out using partially overlapping sub-domains (ΩC and ΩA) as depicted in Fig.1.
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For multiphase systems, a main limitation of the NS equations is the inadequate treatment of interfacial phenomena taking place at the atomistic level. We aim to circumvent this issue through the multi-scale representation of the liquid in which the atomistic resolution is confined to the region influenced by the liquid interface.
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Our work in this area can be divided into two components: (i) Algorithm development: with readily available NS and MD solvers, the bulk of algorithm research into HAC modeling has been concerned with the coupling between the two descriptions in the overlap region ΩO, and the proper termination of ΩA which lacks periodicity at its boundary ΓA. Towards the latter, we have devised a new algorithm for the termination of atomistic sub-domains (ΩA) with specular boundaries [1], and are currently working on extending the algorithm beyond simple atomic liquids. (ii) Applications: here we demonstrated how a properly terminated atomistic sub-domain (ΩA) can be setup to capture interfacial slip in shear flows between immiscible liquids [2] (Fig.2). We anticipate that our progress on (i) will facilitate studies of more complex liquid interfaces.

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