We have run a total of 311 direct numerical simulations (DNSs) of decaying three-dimensional Navier-Stokes turbulence in a periodic box with values of the Taylor length-based Reynolds number up to about 300 and an energy spectrum with a wide wave-number range of close to -5/3 power-law dependence at the higher Reynolds numbers. On the basis of these runs, we have found a critical time when (i) ...

Virtual organizations play an important role in today’s economy, as they are able to adapt themselves to the turbulent market environments. Team work and collaboration are main characteristics of virtual organizations, so the contacts among human beings have outstanding importance. A very important element of this human contact is trust. Trust building in virtual organizations has special chara...

Abstract Decaying grid turbulence is considered at low Reynolds number (Rλ ~ 50) for different initial conditions. Three different grid geometries are used. Heat is injected via a mandoline at a distance of 1.5 M from the grid. The amount of heating is such that temperature may be treated as a passive scalar. A small contraction (1.36:1) is added at a distance of 11M downstream of the grid. The...

The most basic and arguably most important property that any theory or model of turbulence must predict is the mean flow profile. A model or theory of turbulence which can do this for a wide range of turbulent flows on the basis of only few fundamental and robust assumptions is still lacking. However, in the case of canonical boundary-free turbulent shear flows such as turbulent jets, wakes, an...

Abstract Building on a summary of how turbulence influences biological systems, we reviewed key phytoplankton-turbulence laboratory experiments (after Peters and Redondo in Scientia Marina: Lectures plankton turbulence, International Centre for Coastal Resources, Barcelona, 1997) Marrasé (Marine Ecology Progress Series 205:291–306, 2000) to provide current overview artificial generation methods...

Reconnections of quantum vortex filaments create sharp bends which degenerate into propagating Kelvin waves. These waves cascade their energy down-scale and their waveaction up-scale via weakly nonlinear interactions, and this is the main mechanism of turbulence at the scales less than the inter-vortex distance. In case of an idealised forcing concentrated around a single scale k0, the turbulen...

1 Goal In this Lecture, we shall present the main ideas behind the simulation of fluid turbulence. We firts discuss the case of the direct numerical simulation, in which all scales of motion within the grid resolution are simulated and then move on to turbulence modeling, where the effect of unresolved scales on the resolved ones is taken into account by various forms of modeling, 1