1 Modeling bubble-vortex interactions Simulations of bubble entrainment and interactions with two dimensional vorti-cal flows are preformed using a Discrete Element Model (DEM). In this Eulerian-Lagrangian approach, solution to the carrier phase is obtained using direct numerical simulation whereas motion of subgrid bubbles is modeled using Lagrangian tracking. The volumetric displacement of th...

Hydraulic turbines are usually operating at high efficiencies around 90%. It is possible to increase the efficiency by preventing flow characteristics such as failure, cavitation and vortex rope in draft tube. In some cases, partial loads or overloads, pressure pulsations would occur These undesired events damage components of turbine that also causes decrease. To eliminate these artifacts, it ...

Fritts et al. (J. Fluid Mech., vol. xx, 2022, xx) describe a direct numerical simulation of interacting Kelvin–Helmholtz instability (KHI) billows arising due to initial billow cores that exhibit variable phases along their axes. Such KHI strong ‘tube and knot’ dynamics identified in early laboratory studies by Thorpe ( Geophys. Astrophys. Dyn. , 34, 1985, pp. 175–199). Q.J.R. Meteorol. Soc. 12...

Nonlinear quasigeostrophic flows in two layers over a topographic slope are considered. Scaling the lower layer potential vorticity equation yields two parameters which indicate the degree of nonlinearity in the lower layer. The first, u' (the strength of the deep flow divided by the product of the effective bottom slope and the squared length scale), is related to the advection of relative vor...

The vortex stretching process is relevant to energy transport at various scales in turbulent flow and in vortex reconnection. For these, reasons, exact solutions for vortex flow are useful. Robinson and Saffman [1] examined the Burgers vortex solution and found closed form steady solutions for special parameter values. Unsteady 2D Burgers vortex solutions have been used to model the spanwise st...

Automatic extraction of features is a promising strategy to cope with the large amount of data produced by time-dependent CFD (computational fluid dynamics) simulations. Computation time for this type of simulations is typically in the order of days, which justifies the time spent on post-processing the data by extracting features in a batch run. Automatic feature extraction can achieve data re...

The Ranque–Hilsch vortex tube (RHVT) is a device currently used to generate local cooling. In general, the fluid that is injected into the RHVT is a single-phase gas. In this study, however, we have added a dispersed phase (water droplets) to the gas (nitrogen). By means of phase Doppler particle analysis, three velocity components, their higher order moments, and sizes of droplets were measure...