Lagrangian statistics from millions of particles are used to study the turbulent entrainment mechanism in a direct numerical simulation of a turbulent plane jet at Re(λ) ≈ 110. The particles (tracers) are initially seeded at the irrotational region of the jet near the turbulent shear layer and are followed as they are drawn into the turbulent region across the turbulent-nonturbulent interface (...

A hybrid vortex filament scheme with the capability of simulating bounded turbulent flows is described. Viscous generation of new vortex elements at solid surfaces is accomplished through the intermediary step of solving the viscous vorticity transport equation on a thin boundary mesh via a finite difference and finite volume method. The transitional and turbulent boundary-layer flow past a wid...

Direct numerical simulation was used to study laminar and turbulent flows in circular pipes with smoothly corrugated walls. The corrugation wavelength was kept constant at 0.419D, where D is the mean diameter of the wavy-wall pipe and the corrugation height was varied from zero to 0.08D. Flow rates were varied in steps between low values that generate laminar flow and higher values where the fl...

In many engineering and industrial applications, the investigation of rotating turbulent flow is of great interest. In rotor-stator cavities, the centrifugal and Coriolis forces have a strong influence on the turbulence by producing a secondary flow in the meridian plane composed of two thin boundary layers along the disks separated by a non-viscous geostrophic core. Most numerical simulations ...

A compressible single step chemistry Direct Numerical Simulation (DNS) database of freely propagating premixed flames has been used to analyze different entropy generation mechanisms. The entropy generation due to viscous dissipation within the flames remains negligible in comparison to the other mechanisms of entropy generation. It has been found that the entropy generation increases significa...

In this paper the flow behaviour over a number of car bodies is studied. For this purpose the unsteady 2-D incompressible Navier-Stokes equations have been applied. After averaging and nondimensionalizing the equations, the system of equations has been transformed from the Cartesian (x-y) coordinates to a body fitted generalized (-) coordinate. As the flow is incompressible, the density in the ...

The spectral vanishing viscosity (SVV) method has recently appeared of interest for the large-eddy simulation (LES) of turbulent flows. Here we show that the SVV-LES approach allows to easily compute turbulent quantities, like the dissipation rates of the turbulent kinetic energy or of the variance of a passive scalar and to clearly discern the subgrid and viscous contributions. Results obtaine...

The aim of this paper is to introduce numerical procedures to calculate the flow parameters in the bladed space of a cylindrically bladed radial-flow fan-impeller. The characteristics of the flow belonging to different duty points of the fan were determined by the numerical procedure. In this calculation, the blade effects as well as the effects of the fluid friction and the turbulence were tak...

PURPOSE To assess how 4D flow MRI-based pressure and energy loss estimates correspond to net transstenotic pressure gradients (TPGnet) and their dependence on spatial resolution. METHODS Numerical velocity data of stenotic flow were obtained from computational fluid dynamics (CFD) simulations in geometries with varying stenosis degrees, poststenotic diameters and flow rates. MRI measurements ...