The electrification of particles embedded in a turbulent flow may cause hazards such as spark discharges but is also exploited in several industrial applications. Nonetheless, due to its complexity and sensitivity to the initial conditions, the process of build-up of particle charge is currently not well understood. In order to gain a deeper understanding of this phenomenon, we performed fully resolved numerical simulations of particle charging. More specifically, our study concerned the charging process of particles dispersed in a turbulent channel flow at a friction Reynolds number of $Re_{\unicode[STIX]{x1D70F}}=180$ . Emphasis was placed on the analysis of the interplay between the different physical mechanisms underlying particle electrification, such as fluid turbulence, particle dynamics and particle collisions. Further, we investigated the influence of some important physical parameters. According to our simulations the charge build-up depends strongly on the particle Stokes number, $Stk$ . In particular, at small Stokes numbers, $Stk=0.2$ , the turbopheretic drift inhibits particle charging. By contrast, at moderate Stokes numbers, $Stk=2$ , and low particle number densities, the electric charge builds up but cannot escape the viscous sublayer due to limited particle migration. However, in the case of high particle number densities, the charge is transported away from the wall via inter-particle charge diffusion. A further increase to $Stk=20$ leads to strong charging and particle-bound charge transport towards the bulk of the channel.

The facilitation of a stable combustion process is of utmost importance for the realizability and performance of hypersonic propulsion systems. To elucidate the turbulent combustion characteristics, wall-modeled large eddy simulations of a transverse jet injection into a heated supersonic flow are conducted employing a detailed reaction mechanism. The computation framework utilizes an adaptive central-upwind weighted essentially nonoscillatory (WENO-CU) scheme to achieve the sixth-order accuracy in smooth flowfields, while keeping a good shock-capturing ability. The reacting zones agree well with experimental measurements in terms of the instantaneous distribution of OH radicals. And the flame penetration height has been predicted with an error of less than 17%. It is found that the turbulent reacting flow is dominated by nonpremixed combustion mainly taking place in the near-wall region and jet windward shear-layer. Moreover, the autoignition process, which plays a critical role in stabilizing supersonic combustion, shows to favor a fuel-lean or not very fuel-rich environment of a high enthalpy. Local scalar dissipation induced by turbulence gives rise to a rapid fuel mixing with the surrounding air. However, this effect may also lead to the decrease in local temperature.

In this paper the characteristics of the primary breakup of a liquid jet is analyzed numerically. We applied the Volumes of Fluids (VOF) approach utilizing the Direction Averaged Curvature (DAC) model, to estimate the interface curvature, and the Direction Averaged Normal (DAN) model, to propagate the interface. While being used for the first time to predict liquid atomization, this methodology showed a high accuracy. The influence of varying the fluid properties, namely liquid-gas density and viscosity ratio, and injection conditions is discussed related to the required grid resolution. Resulting droplet sizes are compared to distributions obtained through the One-Dimensional Turbulence (ODT) model