Multipoint distribution calculation of the isotropic turbulent energy spectrum using self-consistent initial conditions

1974 ◽  
Vol 17 (4) ◽  
pp. 846 ◽  
Author(s):  
Ronald L. Fox
Keyword(s):  
Energy Spectrum ◽  
Initial Conditions ◽  
Turbulent Energy ◽  
Distribution Calculation ◽  
Self Consistent

A consequence of the zero fourth cumulant approximation

1962 ◽  
Vol 13 (3) ◽  
pp. 369-382 ◽  
Author(s):  
Edward E. O'Brien ◽  
George C. Francis
Keyword(s):  
Energy Spectrum ◽  
Numerical Computation ◽  
Root Mean Square ◽  
Isotropic Turbulence ◽  
Initial Conditions ◽  
Passive Scalar ◽  
Turbulent Energy ◽  
Length Scale ◽  
Mean Square ◽  
Stationary Turbulence

Recent investigations by Kraichnan (1961) and Ogura (1961) have raised doubts concerning the usefulness of the zero fourth cumulant approximation in turbulence dynamics. It appears extremely tedious to examine, by numerical computation, the consequences of this approximation on the turbulent energy spectrum although the appropriate equations have been established by Proudman & Reid (1954) and Tatsumi (1957). It has proved possible, however, to compute numerically the sequences of an analogous assumption when applied to an isotropic passive scalar in isotropic turbulence.The result of such computation, for specific initial conditions described herein, and for stationary turbulence, is that the scalar spectrum does develop negative values after a time approximately $2 \Lambda | {\overline {(u^2)}} ^{\frac {1}{2}}$, Where Λ is a length scale typical of the energy-containing components of both the turbulent and scalar spectra and $\overline {(u^2)}^{\frac {1}{2}}$ is the root mean square turbulent velocity.

A model for the turbulent energy spectrum

1983 ◽  
Vol 26 (5) ◽  
pp. 1228 ◽  
Author(s):  
Richard J. Driscoll
Keyword(s):  
Energy Spectrum ◽  
Turbulent Energy

scholarly journals Formation sites of Population III star formation: The effects of different levels of rotation and turbulence on the fragmentation behaviour of primordial gas

2020 ◽  
Vol 494 (2) ◽  
pp. 1871-1893 ◽  
Author(s):  
Katharina M J Wollenberg ◽  
Simon C O Glover ◽  
Paul C Clark ◽  
Ralf S Klessen
Keyword(s):  
Star Formation ◽  
Initial Conditions ◽  
Turbulent Energy ◽  
Star Forming ◽  
Wide Range ◽  
Population Iii Stars ◽  
The Individual ◽  
The Masses ◽  
Different Levels ◽  
Population Iii

ABSTRACT We use the moving-mesh code arepo to investigate the effects of different levels of rotation and turbulence on the fragmentation of primordial gas and the formation of Population III stars. We consider nine different combinations of turbulence and rotation and carry out five different realizations of each setup, yielding one of the largest sets of simulations of Population III star formation ever performed. We find that fragmentation in Population III star-forming systems is a highly chaotic process and show that the outcomes of individual realizations of the same initial conditions often vary significantly. However, some general trends are apparent. Increasing the turbulent energy promotes fragmentation, while increasing the rotational energy inhibits fragmentation. Within the ∼1000 yr period that we simulate, runs including turbulence yield flat protostellar mass functions while purely rotational runs show a more top-heavy distribution. The masses of the individual protostars are distributed over a wide range from a few $10^{-3} \, {\rm M_{\odot }}$ to several tens of M⊙. The total mass growth rate of the stellar systems remains high throughout the simulations and depends only weakly on the degree of rotation and turbulence. Mergers between protostars are common, but predictions of the merger fraction are highly sensitive to the criterion used to decide whether two protostars should merge. Previous studies of Population III star formation have often considered only one realization per set of initial conditions. However, our results demonstrate that robust trends can only be reliably identified by considering averages over a larger sample of runs.

A hypothesis of turbulent energy spectrum

1970 ◽  
Vol 26 (5) ◽  
pp. 296-299 ◽  
Author(s):  
Tosio Nan-Niti
Keyword(s):  
Energy Spectrum ◽  
Turbulent Energy

Self-consistent calculation of the electron energy spectrum of aluminum

1984 ◽  
Vol 27 (9) ◽  
pp. 762-767 ◽  
Author(s):  
V. M. Silkin ◽  
E. V. Chulkov ◽  
I. Yu. Sklyadneva ◽  
V. E. Panin
Keyword(s):  
Energy Spectrum ◽  
Electron Energy ◽  
Electron Energy Spectrum ◽  
Consistent Calculation ◽  
Self Consistent
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