Several questions that are relevant to turbulence modeling are addressed on the basis of recently obtained direct numerical simulation results of turbulent supersonic channel flow. In particular, this concerns the turbulence frequency production mechanism, wall damping effects on turbulence model parameters, and the relevance of compressibility effects. Limited support is found for usually appl...

We report results of a three dimensional, high resolution (up to 512) numerical investigation of supersonic compressible magnetohydrodynamic turbulence. We consider both forced and decaying turbulence. The model parameters are appropriate to conditions found in Galactic molecular clouds. We find that the dissipation time of turbulence is of order the flow crossing time or smaller, even in the p...

We show that at the onset of a cyclic fold bifurcation, a birhythmic medium composed of glycolytic oscillators displays turbulent dynamics. By computing the largest Lyapunov exponent, the spatial correlation function, and the average transient lifetime, we classify it as weak turbulence of a transient nature. Virtual heterogeneities generating unstable fast oscillations account for the transien...

A total of 21 planar fractal grids pertaining to three different fractal families have been used in two different wind tunnels to generate turbulence. The resulting turbulent flows have been studied using hot wire anemometry. Irrespective of fractal family, the fractal-generated turbulent flows and their homogeneity, isotropy, and decay properties are strongly dependent on the fractal dimension...

We argue that the recently reported Kolmogorov-like magnetic turbulence spectrum in the cool core of the Hydra A galaxy cluster (Vogt & Enßlin 2005) can be understood by kinetic energy injection by active galaxies which drive a turbulent non-helical magnetic dynamo. We develop an analytical model of the turbulence in cool cores and show that it fits well to Faraday rotation magnetic field measu...

Stochastic versions of stability equations are considered as a means to develop integrated models of transition and turbulence. Two types of stochastic models are considered: probability density function evolution equations for stability mode amplitudes, and Langevin models based on representative stability theories including the resonant triad model and the parabolized stability equations. The...

As part of a more general program of developing multiple-scale models of turbulence, Schiestel suggested a derivation of the homogeneous part of the dissipation rate transport equation. Schiestel's approach is generalized to rotating turbulence. The resulting model reproduces the main features observed in decaying rotating turbulence.

Three-dimensional organization of electrical turbulence that is induced via the phenomenon of spiral breakup is studied in a computer model of the heart, which includes realistic ventricular geometries and cardiac anisotropy. We find filaments of rotors during the turbulence and study their number and length as a function of the heart size. We perform a dimensional analysis of turbulence.

A method based on a statistical approach of estimating uncertainty in simulating the transport and dispersion of atmospheric pollutants is developed using observations and modeling results from a tracer experiment in the complex terrain of the southwestern USA. The method takes into account the compensating nature of the error components by representing all terms, except dispersion error and va...