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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 10: Wetting, Fluidics and Liquids at Interfaces and Surfaces I (joint session CPP/DY)
CPP 10.2: Vortrag
Montag, 17. März 2025, 16:30–16:45, H34
Fluid flow inside slit-shaped nanopores: the role of molecular surface morphology — •Giorgia Marcelli1, Tecla Bottinelli Montadon1, Roya Ebrahimi Viand1, and Felix Höfling1,2 — 1Institute of Mathematics, Freie Universität Berlin, Germany — 2Zuse Institute Berlin, Germany
The boundary conditions of nanoscale flows near surfaces can deviate from the no-slip condition observed at macroscopic scales, and used in classical fluid mechanics. In this context, we investigate the influence of surface morphology on fluid flow inside slit-shaped nanopores [1]. Using non-equilibrium molecular dynamics (NEMD) simulations, we demonstrate that the surface morphology effectively controls the slip length, which approaches zero when the molecular structures of the pore wall and the fluid are matched. We examine two types of pore walls, mimicking a crystalline and an amorphous material, that exhibit markedly different surface resistances to flow. The resulting flow velocity profiles are consistent with Hagen–Poiseuille theory for incompressible, Newtonian fluids when adjusted for surface slip and effective viscosity; the latter is found to vary substantially with the pore width. Moreover, analysis of the hydrodynamic permeability shows that the simulated flows are in the Darcy regime. We further show that thermal isolation within the pore causes a linear increase in fluid temperature along the flow, which we relate to strong viscous dissipation and heat convection, utilizing the conservation laws of fluid mechanics.
[1] G. Marcelli, T. Bottinelli Montadon, R. Ebrahimi Viand, and F. Höfling, arXiv:2411.04882 [cond-mat.soft].
Keywords: non-equilibrium molecular dynamics simulation; capillary flow; fluid state theory; hydrodynamic permeability; nanofluidics