Systematic validation study of an unsteady cavitating flow over a hydrofoil uising conditional averaging: LES and PIV

We present results of Large-eddy simulations (LES) modeling of steady sheet and unsteady cloud cavitation on a two-dimensional hydrofoil which are validated against Particle image velocimetry (PIV) data. The study is performed for the angle of attack of 9° and high Reynolds numbers ReC of the order of 106 providing a strong adverse pressure gradient along the surface. We employ the Schnerr–Sauer and Kunz cavitation models together with the adaptive mesh refinement in critical flow regions where intensive phase transitions occur. Comparison of the LES and visualization results confirms that the flow dynamics is adequately reproduced in the calculations. To correctly match averaged velocity distributions, we propose a new methodology based on conditional averaging of instantaneous velocity fields measured by PIV which only provides information on the liquid phase. This approach leads to an excellent overall agreement between the conditionally averaged fields of the mean velocity and turbulence intensity obtained experimentally and numerically. The benefits of second-order discretization schemes are highlighted as opposed to the lower-order TVD scheme

New insights from old cosmic rays: A novel analysis of archival KASCADE data

Cosmic ray data collected by the KASCADE air shower experiment are competitive in terms of quality and statistics with those of modern observatories. We present a novel mass composition analysis based on archival data acquired from 1998 to 2013 provided by the KASCADE Cosmic ray Data Center (KCDC). The analysis is based on modern machine learning techniques trained on simulation data provided by KCDC. We present spectra for individual groups of primary nuclei, the results of a search for anisotropies in the event arrival directions taking mass composition into account, and search for gamma-ray candidates in the PeV energy domain.Comment: Proceedings of the 37th International Cosmic Ray Conference (ICRC2021), 12-23 July 2021, Berlin, Germany - Onlin

New insights from old cosmic rays: A novel analysis of archival KASCADE data

Cosmic ray data collected by the KASCADE air shower experiment are competitive in terms of quality and statistics with those of modern observatories. We present a novel mass composition analysis based on archival data acquired from 1998 to 2013 provided by the KASCADE Cosmic ray Data Center (KCDC). The analysis is based on modern machine learning techniques trained on simulation data provided by KCDC. We present spectra for individual groups of primary nuclei, the results of a search for anisotropies in the event arrival directions taking mass composition into account, and search for gamma-ray candidates in the PeV energy domain.Comment: Proceedings of the 37th International Cosmic Ray Conference (ICRC2021), 12-23 July 2021, Berlin, Germany - Onlin

Vortical structures in a shallow wake of the flow around a confined cylinder at

We study the flow over a cylinder placed between two parallel rigid walls using Large - eddy simulations. The Reynolds number based on the inflow velocity and diameter of the cylinder is 3750 corresponding to the subcritical regime with laminar separation.The comparison of the time - averaged flow patterns shows very good agreement with experiments.The unsteadiness of the recirculating bubble features the low - frequency modulation observed for the first time

Vortical structures in a shallow wake of the flow around a confined cylinder at Re=3750

We study the flow over a cylinder placed between two parallel rigid walls using Large - eddy simulations. The Reynolds number based on the inflow velocity and diameter of the cylinder is 3750 corresponding to the subcritical regime with laminar separation.The comparison of the time - averaged flow patterns shows very good agreement with experiments.The unsteadiness of the recirculating bubble features the low - frequency modulation observed for the first time

Secondary flows and heat transfer in shallow flow around a cylinder: LES, PIV

We report on Large-eddy simulations (LES) of flow around a short cylinder mounted in a narrow plane channel in a range of Reynolds numbers 1000, 2000, 3750 based on the bulk velocity of the flow and diameter of the cylinder supplemented with Particle image velocimetry (PIV) measurements for the highest considered Re. First two cases appear to be steady, however, for Re=3750 the flow becomes unsteady with the wake dominated by periodic vortex shedding. In front of the cylinder typical horseshoe vortices are identified intensifying the skin friction and heat transfer on the wall, while in the near wake we observe a quasiperiodic low-frequency secondary motion in the form of a pair of counterrotating eddies developing in the transverse direction. The Karman vortex street remains the dominant pattern, but further downstream from the cylinder the transport across the channel is associated with the secondary streamwise vortices, as also previously observed in slot jets. We observe their impact on heat transfer and skin friction on the wall of the channel

Numerical simulation of a two-component jet atomization

Numerical modelling of the breakup of a jet consisting of two immiscible liquids outflowing into the atmosphere has been carried out. For this, the modified three-fluid VOF method has been implemented in the Basilisk open-source package. The jet outflows from a swirl nozzle, in which the liquids are mixed. The mixing of liquids in a swirl nozzle is investigated. The fields of velocities and mass fractions of the components, as well as the size distribution of droplets, are obtained. It is shown that the distribution of droplets in the outer region of the flow is non-uniform as a result of insufficient mixing inside the nozzle