Spectra of Energy Dissipation, Enstrophy and Pressure by High-Resolution Direct Numerical Simulations of Turbulence in a Periodic Box

2003 ◽  
Vol 72 (5) ◽  
pp. 983-986 ◽  
Author(s):  
Takashi Ishihara ◽  
Yukio Kaneda ◽  
Mitsuo Yokokawa ◽  
Ken'ichi Itakura ◽  
Atsuya Uno
Keyword(s):  
Energy Dissipation ◽  
High Resolution ◽  
Numerical Simulations ◽  
Direct Numerical Simulations

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

A new approach to modelling near-wall turbulence energy and stress dissipation

2002 ◽  
Vol 459 ◽  
pp. 139-166 ◽  
Author(s):  
S. JAKIRLIĆ ◽  
K. HANJALIĆ
Keyword(s):  
Energy Dissipation ◽  
Numerical Simulations ◽  
Transport Equation ◽  
Dissipation Rate ◽  
Energy Dissipation Rate ◽  
Direct Numerical Simulations ◽  
Turbulence Energy ◽  
Viscous Term ◽  
Dissipation Equation ◽  
Near Wall

A new model for the transport equation for the turbulence energy dissipation rate ε and for the anisotropy of the dissipation rate tensor εij, consistent with the near-wall limits, is derived following the term-by-term approach and using results of direct numerical simulations (DNS) for several generic wall-bounded flows. Based on the two-point velocity covariance analysis of Jovanović, Ye & Durst (1995) and reinterpretation of the viscous term, the transport equation is derived in terms of the ‘homogeneous’ part εh of the energy dissipation rate. The algebraic expression for the components of εij was then reformulated in terms of εh, which makes it possible to satisfy the exact wall limits without using any wall-configuration parameters. Each term in the new equation is modelled separately using DNS information. The rational vorticity transport theory of Bernard (1990) was used to close the mean curvature term appearing in the dissipation equation. A priori evaluation of εij, as well as solving the new dissipation equation as a whole using DNS data for quantities other than εij, for flows in a pipe, plane channel, constant-pressure boundary layer, behind a backward-facing step and in an axially rotating pipe, all show good near-wall behaviour of all terms. Computations of the same flows with the full model in conjunction with the low-Reynolds number transport equation for (uiui) All Overbar, using εh instead of ε, agree well with the direct numerical simulations.

scholarly journals Direct numerical simulations of particle-laden density currents with adaptive, discontinuous finite elements

2014 ◽  
Vol 7 (3) ◽  
pp. 3219-3264 ◽  
Author(s):  
S. D. Parkinson ◽  
J. Hill ◽  
M. D. Piggott ◽  
P. A. Allison
Keyword(s):  
High Resolution ◽  
Numerical Simulations ◽  
Turbidity Current ◽  
Direct Numerical Simulations ◽  
Three Dimensions ◽  
Turbidity Currents ◽  
Normal Velocity ◽  
Density Currents ◽  
Conservation Of Energy ◽  
Computationally Expensive

Abstract. High resolution direct numerical simulations (DNS) are an important tool for the detailed analysis of turbidity current dynamics. Models that resolve the vertical structure and turbulence of the flow are typically based upon the Navier–Stokes equations. Two-dimensional simulations are known to produce unrealistic cohesive vortices that are not representative of the real three-dimensional physics. The effect of this phenomena is particularly apparent in the later stages of flow propagation. The ideal solution to this problem is to run the simulation in three dimensions but this is computationally expensive. This paper presents a novel finite-element (FE) DNS turbidity current model that has been built within Fluidity, an open source, general purpose, computational fluid dynamics code. The model is validated through re-creation of a lock release density current at a Grashof number of 5 × 106 in two, and three-dimensions. Validation of the model considers the flow energy budget, sedimentation rate, head speed, wall normal velocity profiles and the final deposit. Conservation of energy in particular is found to be a good metric for measuring mesh performance in capturing the range of dynamics. FE models scale well over many thousands of processors and do not impose restrictions on domain shape, but they are computationally expensive. Use of discontinuous discretisations and adaptive unstructured meshing technologies, which reduce the required element count by approximately two orders of magnitude, results in high resolution DNS models of turbidity currents at a fraction of the cost of traditional FE models. The benefits of this technique will enable simulation of turbidity currents in complex and large domains where DNS modelling was previously unachievable.

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
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