Density-scaled balanced continuum surface force model with a level set based curvature interpolation technique

We examine the recently-proposed density-scaled balanced CSF (continuum surface force) model with a level set based curvature interpolation technique. The density-scaled balanced CSF model is combined with a numerical framework which is based on the CLSVOF (coupled level set and volume-of-fluid) method, the THINC/WLIC (tangent of hyperbola for interface capturing/weighted line interface calculation) scheme, multi-moment methods (CIP-CSLR and VSIAM3). The present CSF model is examined for various bench mark problems such as drop-drop collisions and drop splashing. Comparisons of the present model results with experimental observations and those from the other CSF models show that the present CSF model can minimize spurious current and capture complicated fluid phenomena with minimizing floatsam

A novel smoothed particle hydrodynamics formulation for thermo-capillary phase change problems with focus on metal additive manufacturing melt pool modeling

Laser-based metal processing including welding and three dimensional printing, involves localized melting of solid or granular raw material, surface tension-driven melt flow and significant evaporation of melt due to the applied very high energy densities. The present work proposes a weakly compressible smoothed particle hydrodynamics formulation for thermo-capillary phase change problems involving solid, liquid and gaseous phases with special focus on selective laser melting, an emerging metal additive manufacturing technique. Evaporation-induced recoil pressure, temperature-dependent surface tension and wetting forces are considered as mechanical interface fluxes, while a Gaussian laser beam heat source and evaporation-induced heat losses are considered as thermal interface fluxes. A novel interface stabilization scheme is proposed, which is shown to allow for a stable and smooth liquid-gas interface by effectively damping spurious interface flows as typically occurring in continuum surface force approaches. Moreover, discretization strategies for the tangential projection of the temperature gradient, as required for the discrete Marangoni forces, are critically reviewed. The proposed formulation is deemed especially suitable for modeling of the melt pool dynamics in metal additive manufacturing because the full range of relevant interface forces is considered and the explicit resolution of the atmospheric gas phase enables a consistent description of pore formation by gas inclusion. The accuracy and robustness of the individual model and method building blocks is verified by means of several selected examples in the context of the selective laser melting process

Flow in the gradually converging stepped spillway

Степенасти брзотоци су популарна мера за дисипацију енергије преливене воде. Своју популарност дугују добрим дисипационим карактеристикама и нижом ценом изградње у односу на класичне брзотоке са глатним дном. Ефикасност дисипације енергије степенастог брзотока расте са повећањем његове ширине. У овој дисер- тацији анализиране су хидрауличке последице струјања у степенастом брзотоку са постепеним смањењем ширине канала. Истраживање је спроведено мерењима на два физичка модела и нумеричким симулацијама...Stepped spillways are popular energy dissipators. Compared to classic smooth spillways, stepped spillways present a good balance between energy dissipation and low construction costs. Energy efficiency dissipation is proportional to spillway width. This dissertation deals with hydraulics of the gradually converging stepped spillways. The research included measurements on two scale-models and numerical simulations..