1,727,871 research outputs found
Scaling properties of compressible polytropic turbulence
No full textAn exact relation has been derived for homogeneous polytropic turbulence in terms of the two-point fluctuations. Unlike isothermal turbulence, the fluctuating sound speed appears to be a key factor in determining the scaling properties of polytropic turbulence. Three Mach numbers (current, gradient and turbulent Mach number) are defined to characterize the isotropic scaling. At subsonic scale, the Kolmogorov-like -5/3 energy spectrum for ⇢1/3v (obtained for isothermal turbulence) is modified by polytropic contribution. For supersonic turbulence, the source terms must be taken into account which further complicates the scaling and spectral properties. For highly supersonic case, the source terms, however, can be shown to be nearly equal to the source terms in isothermal turbulence thereby leading to a partial simplification. These theoretical results are extremely important for understanding the role of turbulence in the star-formation mechanism in polytropic clouds
The use and limitations of continuum modes for response calculations of cellular structures
No full textIn this paper, a method for the approximate calculations of response of cellular structures is presented. The method is based on the idea that for low-frequency modes, the cellular structures behave in a way similar as a continuum does. The range of validity of the method on the mode number scale is also examined. It is shown that the response is estimated very accurately from a reduced order model based on continuum modes for low-frequency vibration. The accuracy starts to deteriorate with the increase in the mode number. Beyond certain mode number, the improvement in accuracy due to the inclusion of additional continuum modes in the approxijmation shows a point of diminishing returns. illustrative examples are given
Microscopic dynamics, chaos and transport in nonequilibrium processes
No full textThis EPJ - Special Topics issue is a collection of contributions on theory and the recent developments in nonequilibrium statistical mechanics, fluctuations theory and dynamical systems. The various articles report results on the role of microscopic dynamics in giving rise to complex patterns observed at the macroscopic scale in a variety of physical phenomena
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