Numerical Experiments on Collective Effects in Stellar Dynamics.

Magnetic helicity in stellar dynamos: new numerical experiments

The theory of large scale dynamos is reviewed with particular emphasis on the magnetic helicity constraint in the presence of closed and open boundaries. In the presence of closed or periodic boundaries, helical dynamos respond to the helicity constraint by developing small scale separation in the kinematic regime, and by showing long time scales in the nonlinear regime where the scale separati...

Extracting Qualitative Dynamics from Numerical Experiments

The Phase Space is a powerful tool for representing and reasoning about the qualitative behavior of nonlinear dynamical systems. Significant physical phenomena of the dynamical system periodicity, recurrence, stability and the like are reflected by outstanding geometric features of the trajectories in the phase space. Successful use of numerical computations to completely explore the dynamics o...

Collective effects in dissipative particle dynamics

We study the detailed dynamics of DPD particles by looking at the velocity autocorrelation function. We observe that in the regimes of interest for simulations, the velocity autocorrelation function reflects the hydrodynamic behavior of these particles.  1999 Elsevier Science B.V. All rights reserved.

Collective effects of stellar winds and unidentified gamma-ray sources

We study collective wind configurations produced by a number of massive stars, and obtain densities and expansion velocities of the stellar wind gas that is to be target, in this model, of hadronic interactions. We study the expected γ-ray emission from these regions, considering in an approximate way the effect of cosmic ray modulation. We compute secondary particle production (electrons from ...

Brownian dynamics in a confined geometry. Experiments and numerical simulations