In this work, coarse-grained (CG) models for two different sets of ionic liquids were developed from atomistic molecular dynamics (MD) reference systems, expanding their system size and time duration capabilities. The bonded force field of the CG systems was built using harmonic oscillator potential (HOP) fitting, while the nonbonded force field was generated with the multiscale coarse-graining (MS-CG) approach based on force matching. The dynamics of each system were corrected using the probability distribution function-based coarse-grained molecular dynamics (PDF-based CGMD) method. The structure and dynamics of each system were proven to match reference system data at two temperature scales. CG models and force fields for these liquids were developed to exemplify a general purpose methodology for producing MD results of ionic liquids and other fluids with accurate structural as well as dynamic properties. As an application, developed ionic liquids CG models were then applied to study vacuum−interface interaction. Density profile results of vacuum−interface exposure show significant deviation from bulk behavior. At the interface, multilayer ordering of ionic liquids is predicted to be similar to those observed from an experimental work. This ordering is intensified by decreasing temperature and use of the PDF-based CGMD method as opposed to conventional CG methods.

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The Kentucky Re-Entry Universal Payload System (KRUPS) is a low-cost space capsule that has been designed to collect flight data. This work focuses on computational fluid dynamics (CFD) simulations of the flow around the capsule at various altitudes along the trajectory path during Earth re-entry. CFD simulations are performed at altitudes of 60 and 40 km by accounting for thermochemical nonequilibrium and surface catalycity using current state-of-the-art hypersonic approaches. The flowfield at all altitudes exhibits significant thermal and chemical nonequilibrium with vibrational temperature lagging the translational temperature in the forebody and exceeding the translational temperature in the wake. Inclusion of surface catalycity influences the heat flux on the surface and the flow temperature in the boundary layer. The number density profiles of nitric oxide molecules and spectral emission computations using the line-by-line radiative solver NEQAIR indicate that higher emissions would occur at an altitude of 60 km in comparison to emissions at 40 km, and spectral intensity would be higher along the stagnation line despite high densities of NO near the edges of the capsule, and that emissions in the 100–400 nm wavelength range are dominant.