scholarly journals Analysis of the dissipative range of the energy spectrum in grid turbulence and in direct numerical simulations

2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Anastasiia Gorbunova ◽  
Guillaume Balarac ◽  
Mickaël Bourgoin ◽  
Léonie Canet ◽  
Nicolas Mordant ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Numerical Simulations ◽  
Direct Numerical Simulations ◽  
Grid Turbulence

On the emergence of non-classical decay regimes in multiscale/fractal generated isotropic turbulence

2014 ◽  
Vol 756 ◽  
pp. 816-843 ◽  
Author(s):  
Marcello Meldi ◽  
Hugo Lejemble ◽  
Pierre Sagaut
Keyword(s):  
Energy Spectrum ◽  
Kinetic Energy ◽  
Numerical Simulations ◽  
Time Scale ◽  
Isotropic Turbulence ◽  
Initial Kinetic Energy ◽  
Grid Turbulence ◽  
Production Term ◽  
Turbulence Decay ◽  
Turbulence Production

AbstractThe present paper addresses the issue of finding key parameters that may lead to the occurrence of non-classical decay regimes for fractal/multiscale generated grid turbulence. To this aim, a database of numerical simulations has been generated by the use of the eddy-damped quasi-normal Markovian (EDQNM) model. The turbulence production in the wake of the fractal/multiscale grid is modelled via a turbulence production term based on the forcing term developed for direct numerical simulations (DNS) purposes and the dynamics of self-similar wakes. The sensitivity of the numerical results to the simulation parameters has been investigated successively. The analysis is based on the observation of both the time evolution of the turbulent energy spectrum $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}E(k,t)$ and the decay of the flow statistical quantities, such as the turbulent kinetic energy $\mathcal{K}(t)$ and the energy dissipation rate $\varepsilon (t)$. A satisfactory agreement with existing experimental data published by different research teams is observed. In particular, it is observed that the key parameter that governs the nature of turbulence decay is $\alpha ={d/U_{\infty }}\, {(\varepsilon (0)/\mathcal{K}(0))}={d/L(0)} \, {(\sqrt{\mathcal{K}(0)}/U_{\infty })}$ (with $d$ the bar diameter and $U_{\infty }$ the upstream uniform velocity), which measures the ratio of the time scale largest grid bar $d/U_{\infty }$ to the turbulent time scale $\mathcal{K}(0)/\varepsilon (0)$. Two asymptotic behaviours for $\alpha \rightarrow + \infty $ and $\alpha \rightarrow 0$ are identified: (i) a fast algebraic decay law regime for rapidly decaying production terms, due to strongly modified initial kinetic energy spectrum and (ii) a real exponential decay regime associated with strong, very slowly decaying production terms. The present observations are in full agreement with conclusions drawn from recent fractal grid experiments, and it provides a physical scenario for occurrence of anomalous decay regime which encompasses previous hypotheses.

scholarly journals Direct Numerical Simulations of Compressible Grid Turbulence

2020 ◽  
Vol 2020 (0) ◽  
pp. S05430
Author(s):  
Yuka YAMAUCHI ◽  
Tomoaki WATANABE ◽  
Koji NAGATA ◽  
Akihiro SASOH
Keyword(s):  
Numerical Simulations ◽  
Direct Numerical Simulations ◽  
Grid Turbulence

Energy dissipation rate and energy spectrum in high resolution direct numerical simulations of turbulence in a periodic box

2003 ◽  
Vol 15 (2) ◽  
pp. L21-L24 ◽  
Author(s):  
Yukio Kaneda ◽  
Takashi Ishihara ◽  
Mitsuo Yokokawa ◽  
Ken’ichi Itakura ◽  
Atsuya Uno
Keyword(s):  
Energy Spectrum ◽  
Energy Dissipation ◽  
High Resolution ◽  
Numerical Simulations ◽  
Dissipation Rate ◽  
Energy Dissipation Rate ◽  
Direct Numerical Simulations

Energy spectrum in high-resolution direct numerical simulations of turbulence

2016 ◽  
Vol 1 (8) ◽  
Author(s):  
Takashi Ishihara ◽  
Koji Morishita ◽  
Mitsuo Yokokawa ◽  
Atsuya Uno ◽  
Yukio Kaneda
Keyword(s):  
Energy Spectrum ◽  
High Resolution ◽  
Numerical Simulations ◽  
Direct Numerical Simulations

scholarly journals The onset of thermalization in finite-dimensional equations of hydrodynamics: insights from the Burgers equation

2017 ◽  
Vol 473 (2197) ◽  
pp. 20160585 ◽  
Author(s):  
Divya Venkataraman ◽  
Samriddhi Sankar Ray
Keyword(s):  
Energy Spectrum ◽  
Numerical Simulations ◽  
Euler Equations ◽  
Burgers Equation ◽  
Three Dimensional ◽  
Direct Numerical Simulations ◽  
Infinite Dimensional ◽  
Localized Structures ◽  
Finite Dimensional ◽  
Incompressible Euler

Solutions to finite-dimensional (all spatial Fourier modes set to zero beyond a finite wavenumber K G ), inviscid equations of hydrodynamics at long times are known to be at variance with those obtained for the original infinite dimensional partial differential equations or their viscous counterparts. Surprisingly, the solutions to such Galerkin-truncated equations develop sharp localized structures, called tygers (Ray et al. 2011 Phys. Rev. E 84 , 016301 ( doi:10.1103/PhysRevE.84.016301 )), which eventually lead to completely thermalized states associated with an equipartition energy spectrum. We now obtain, by using the analytically tractable Burgers equation, precise estimates, theoretically and via direct numerical simulations, of the time τ c at which thermalization is triggered and show that τ c ∼ K G ξ , with ξ = − 4 9 . Our results have several implications, including for the analyticity strip method, to numerically obtain evidence for or against blow-ups of the three-dimensional incompressible Euler equations.

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