We present various numerical studies conducted with a novel pore-scale simulation technology called Direct Hydrodynamic (DHD) Simulation that can be used to study multiphase flow at various scales ranging from individual pore-scale events to complex scenarios like capillary de-saturation and relative permeability of digitized rock samples. DHD uses a diffuse interface description for fluid-fluid interfaces that is implemented via the density functional approach applied to the hydrodynamics of complex systems. In addition to mass and momentum balance, a full thermodynamic energy balance is considered. Hence the simulator inherently takes into consideration multi-phase and multi-component behavior and is suited for non-isothermal cases which allows the handling of many physical phenomena including multiphase compositional flows with phase transitions, different types of fluid-rock and fluid-fluid interactions (e.g. wettability and adsorption), and various types of fluid rheology.

The DHD simulator is a research prototype optimized for high performance computing (HPC) and applied to porous media systems. We demonstrate the utility of DHD to simulate two-phase flow displacement ranging from the classical "Lenormand" pore-scale displacement events and Roof's snap-off criteria to more complex cooperative phenomena like capillary de-saturation and relative permeability. The presented simulation results are benchmarked against experimental data in core flooding, 2D micromodel, and synchrotron-based x-ray microtomography experiments and provide good agreement.