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The effect of nozzle surface features on the overall atomization behavior of a liquid jet is analyzed in the present computational work by adopting three representative geometries, namely a single X-ray tomography scan of the Engine Combustion Network’s Spray A nozzle (Unprocessed), a spline reconstruction of multiple scans (Educated), and a purely external flow configuration. The latter configuration is often used in fundamental jet atomization studies. Numerically, the two-phase flow is solved based on algebraic volume-of-fluid methodology utilizing the OpenFoam solver, interFoam. Quantitative characterization of the surface features concerning the first two geometries reveals that while both of them have similar levels of cylindrical asymmetries, the nozzle configuration pertaining to the Unprocessed geometry has much larger surface features along the streamwise direction than the Educated geometry. This produces for the Unprocessed configuration a much larger degree of non-axial velocity components in the flow exiting the orifice and also a more pronounced disturbance of the liquid surface in the first few diameters downstream of the nozzle orifice. Furthermore, this heightened level of surface destabilization generates a much shorter intact liquid core length, that is, it produces faster primary atomization. The surprising aspect of this finding is that the differences between the Unprocessed and Educated geometries are of [Formula: see text](1) μm, and they are able to produce [Formula: see text](1) mm effects in the intact liquid core length. In spite of more pronounced atomization for the Unprocessed geometry, the magnitude of the turbulent liquid kinetic energy is roughly the same as the Educated geometry. This highlights the important role of mean field quantities, in particular, non-axial velocity components, in precipitating primary atomization. At the other end of the spectrum, the external-only configuration has the mildest level of surface disturbances in the near field resulting in the longest intact liquid core length. 

Adaptive mesh refinement (AMR) has been introduced as an attractive means of significantly improving computational efficiency for a variety of two-phase flow problems. In the current study, the benefits of AMR are investigated for the case of liquid jet atomization. The evaluation consists of a systematic analysis of results from the interDymFoam (AMR octree) and interFoam (static octree) codes, both of which form part of the family of solvers distributed within the open source OpenFOAM C++ Toolbox. The two-phase flow treatment is based on an algebraic VoF methodology. As a preliminary set of exercises, cases for pure advection, stationary wave dynamics, and Rayleigh-Plateau breakup of a cylindrical liquid element are considered. The results from these exercises confirm the expected trend of higher numerical efficiency in AMR, while still retaining essentially the same level of accuracy as the fixed embedded mesh solutions. However, for the liquid jet atomization, the behavior is a bit more complicated. First, at lower levels of Weber number, we observe a similar trend as the preliminary exercises. At higher Weber numbers, due to a noticeable increase in interfacial area density, substantial inhomogeneities are formed in the underlying grids yielding slower solutions of pressure Poisson equation, thereby potentially offsetting the benefits of this approach. In fact, at much higher Weber numbers, for instance, those pertaining to Diesel injection, the results suggest that a fixed embedded mesh would provide better computational efficiency. However, this conclusion depends on the target lowest level of numerical resolution, Δxmin. The current work shows how the efficiency of AMR suffers from increasing interfacial area density, and how this can be alleviated via a decrease in Δxmin. Various test cases are presented to illustrate this effect.