Abstract Transport and mixing of scalar quantities in fluid flows is ubiquitous industry Nature. While the more familiar turbulent promote efficient transport by their inherent spatio-temporal disorder, laminar lack such a natural mechanism far challenging. However, flow essential to many problems, insight into its characteristics great importance. Laminar transport, arguably, best described La...

We consider the evolution of arbitrarily large perturbations a prescribed pure hydrodynamical flow an electrically conducting fluid. study whether as well generated magnetic fields decay or grow with time and constitute dynamo process. For that purpose we derive generalized Reynolds-Orr equation for sum kinetic energy hydrodynamic perturbation energy. The is confined in finite volume so normal ...

We compare the lattice Boltzmann equation (LBE) and the gas-kinetic scheme (GKS) applied to 2D incompressible laminar flows. Although both methods are derived from the Boltzmann equation thus share a common kinetic origin, numerically they are rather different. The LBE is a finite difference method, while the GKS is a finite-volume one. In addition, the LBE is valid for near incompressible flow...

We find that tracer material can be concentrated into invariant regions of flows due exclusively to transient effects, as are produced when tracers temporarily become more buoyant than the surrounding fluid. This can occur either as a single event, e.g., if the tracer is initially weakly buoyant, or under periodic forcing, e.g., when external effects (such as solar heating) change the tracer de...

The problem of inverse statistics (statistics of distances for which the signal fluctuations are larger than a certain threshold) in differentiable signals with power law spectrum, E(k) approximately k(-alpha), 3< or =alpha<5, is discussed. We show that for these signals, with random phases, exit-distance moments follow a bifractal distribution. We also investigate two dimensional turbulent flo...