Benjamin Bursik, SFB 1313 doctoral researcher at the Institute of Technical Thermodynamics and Thermal Process Engineering (research project A01), will defend his dissertation "Modeling the Dynamics of Interfaces in Porous Media Using Hydrodynamic Density Functional Theory”. He is a member of the SFB 1313 Integrated Research Training Group IRTG-IMPM.
Title: "Modeling the Dynamics of Interfaces in Porous Media Using Hydrodynamic Density Functional Theory”
Date: 4 December 2025
Time: 3:30 pm CET
Venue: Sitzungszimmer der Fakultät 4, Raum 5.259 Pfaffenwaldring 9, 70569 Stuttgart
Abstract
Accurately predicting flow in porous media requiresmodels that capture the complex dynamics at solid–fluid interfaces governed by molecular-scale effects, while being applicable on the macroscopic scale to describe the overall process. Hydrodynamic density functional theory (hydrodynamic DFT) connects molecular and continuum models by incorporating molecular detail into balance equations. In this work, a framework based on hydrodynamic DFT is developed, assessed, and applied to model dynamic interfacial processes at the molecular scale. It solves mass, component, and momentum balances, where the relevant molecular effects are represented explicitly via a chemical potential of inhomogeneous systems from classical (equilibrium) DFT. This formulation predicts the influence of interfacial properties onthe dynamics of the system and reduces to the isothermal Navier–Stokes equations far away from interfaces. Fluid–fluid interactions are described using Helmholtz energy functionals based on the PC-SAFT and PeTS models, enabling the prediction of interfacial properties for real and model fluids. A Newtonian shear pressure relation is assumed, and molecular diffusion is described via the Maxwell–Stefan approach. The associated transport coefficients, shear viscosity and diffusion coefficient, are obtained from a generalized entropy scaling approach, which is extended from homogeneous to inhomogeneous systems, including solid–fluid interfaces. This thesis yields three key results: First, the DFT approach reliably predicts equilibrium interfacial properties of real systems in agreement with experiments, in particular contact angles of macroscopic droplets for pure substances and mixtures (as well as solvation free energies). Second, the entropy scaling approach proves to be valid for interfacial viscosities if solid effects are included and for diffusion coefficients at vapor–liquid interfaces. It provides a molecular model for spatially resolved transport properties, which is crucial for quantitatively describing wetting on the molecular scale and goes beyond typical continuum approaches, where coefficients are assigned to entire phases. Third, the framework predicts microscopic wetting phenomena such as dynamic contact angles and the rolling motion of droplets on a solid. It also captures dynamic processes involving mixtures, as demonstrated for mass transfer through vapor–liquid interfaces. Overall, the developed framework accurately capturesmolecular-scale interfacial dynamics while remaining consistent with continuum fluid dynamics. By uniting microscopic rigor with broad practical applicability, it enables predictive investigations of relevant processes in porous media and contributes to the advancement of multiscale modeling approaches.