scholarly journals Local modulated wave model for the reconstruction of space–time energy spectra in turbulent flows

2020 ◽  
Vol 886 ◽  
Author(s):  
Ting Wu ◽  
Guowei He

2000 ◽  
Vol 61 (6) ◽  
pp. 6572-6577 ◽  
Author(s):  
Norbert Schorghofer

2007 ◽  
Vol 14 (2) ◽  
pp. 139-151 ◽  
Author(s):  
R. Castilla ◽  
J. M. Redondo ◽  
P. J. Gámez-Montero ◽  
A. Babiano

Abstract. We study numerically the comparison between Lagrangian experiments on turbulent particle dispersion in 2-D turbulent flows performed, on the one hand, on the basis of direct numerical simulations (DNS) and, on the other hand, using kinematic simulations (KS). Eulerian space-time structure of both DNS and KS dynamics are not comparable, mostly due to the absence of strong coherent vortices and advection processes in the KS fields. The comparison allows to refine past studies about the contribution of non-homogeneous space-time 2-D Eulerian structure on the turbulent absolute and relative particle dispersion processes. We particularly focus our discussion on the Richardson's regime for relative dispersion.


2014 ◽  
Vol 30 (4) ◽  
pp. 468-479 ◽  
Author(s):  
Wei Wang ◽  
Xin-Lei Guan ◽  
Nan Jiang

Author(s):  
Yoshifumi Ogami ◽  
Kazuie Nishiwaki ◽  
Yoshinobu Yoshihara

First, a simple and accurate numerical method is presented to produce velocity fluctuations that are determined by the prescribed physical quantities and qualities of turbulence such as longitudinal and lateral spectra, and integral scales. The fluctuations are obtained by solving a system of nonlinear equations that are derived from the equations of energy spectra and of root mean square of the fluctuations. This method requires as many computer memories and computations as one-dimensional case even for the three dimensional calculations. It is shown that there is a strong resemblance of the simulated velocity fluctuations and experimental data. The energy spectra of these velocity fluctuations are quite accurate with less than 0.01% relative errors to the prescribed spectra. Secondly, these solutions are used to examine the capability of the vortex methods to produce turbulent flows with the prescribed parameters. It is found that although the energy spectra by the vortex method scatter to some extent, they are distributed along the prescribed spectra. It can be said that the vortex methods are able to simulate the target turbulence fairly well. Also it is found that the solutions with the LES model increase and deviate from the target spectrum at the higher frequency regions. This may suggest the nonessentiality of the LES model for the vortex method.


2020 ◽  
Vol 903 ◽  
Author(s):  
Yi Zhou ◽  
Koji Nagata ◽  
Yasuhiko Sakai ◽  
Tomoaki Watanabe ◽  
Yasumasa Ito ◽  
...  

Abstract


1984 ◽  
Vol 16 (1) ◽  
pp. 18-18 ◽  
Author(s):  
Vijay K. Gupta ◽  
R. N. Bhatiacharya

Consider a saturated porous m edium in which water is flowing slowly with a steady velocity. Suppose at some space-time scale the concentration C(x, r) of a non-reactive dilute solute is governed by the following Fokker-Planck differential equation:


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