DNS of viscoelastic turbulent channel flow with rectangular orifice at low Reynolds number

Tsukahara, Takahiro; Kawase, Tomohiro; Kawaguchi, Yasuo

doi:10.1016/j.ijheatfluidflow.2011.02.009

Cited by 28 publications

(30 citation statements)

References 35 publications

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“…Later studies focused on higher Reynolds number flows (Re ≥ 1000): turbulent spots and their characteristics have been thoroughly studied [13][14][15][16][17] and, more recently, numerical simulations revealed the presence of closely arranged turbulent bands or stripes. 18,19 The flow structures at moderate Reynolds numbers have been revisited lately. 20 In order to simplify the spatio-temporal complexity of PPF and reduce the computational costs, slender computational domains at fixed tilt angles to the streamwise direction have been used to simulate band patterns at moderate Reynolds numbers.…”

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confidence: 99%

Turbulent bands in plane-Poiseuille flow at moderate Reynolds numbers

et al. 2015

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In this letter, we show via numerical simulations that the typical flow structures appearing in transitional channel flows at moderate Reynolds numbers are not spots but isolated turbulent bands, which have much longer lifetimes than the spots. Localized perturbations can evolve into isolated turbulent bands by continuously growing obliquely when the Reynolds number is larger than 660. However, interactions with other bands and local perturbations cause band breaking and decay. The competition between the band extension and breaking does not lead to a sustained turbulence until Re becomes larger than about 1000. Above this critical value, the bands split, providing an effective mechanism for turbulence spreading.

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confidence: 99%

Turbulent bands in plane-Poiseuille flow at moderate Reynolds numbers

et al. 2015

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“…It can be discovered that at the same scale, the quantity of relatively small-scale CSs is fewer in polymer solution flow, which is in accordance with the ever reported analysis on the characteristics of CSs in turbulent dragreducing flows. [10][11][12][13][14][15][16][17][18][19]37 This also explains that the amount of CSs is inhibited by polymer additives, and the intermittency in viscoelastic fluid flow is likewise suppressed since vortex structures induce the intermittency in turbulence. As is known, WT is an effective tool to detect CSs that have strongest energy locally and play essential role in turbulence.…”

Section: Resultsmentioning

confidence: 99%

“…Sureshkumar et al 9 first used DNS to simulate turbulent drag-reducing flow with the finitely extensible nonlinear elastic in the Peterlin approximation (FENE-P) model based on pseudospectral method. Following that, more and more DNS works have been carried out to resolve the detailed characteristics of turbulent drag-reducing flows and investigate the mechanism of DR. [10][11][12][13][14][15][16][17][18][19] Due to the constraint of computer hardware, the performed DNSs had to be limited to most flows with moderate Reynolds number. Regarding RANS method, several researchers paid attention to the proposition of RANS models for viscoelastic fluid flow and the inquiry on the overall characteristics of polymer solution flows.…”

Section: Introductionmentioning

confidence: 99%

Wavelet analysis of coherent structures and intermittency in forced homogeneous isotropic turbulence with polymer additives

Wang

Zheng

Cai

et al. 2017

Advances in Mechanical Engineering

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Large eddy simulation was performed for forced homogeneous isotropic turbulence with/without polymer additives. Wavelet transform in one dimension and two dimensions were performed to investigate the multi-resolution features of coherent structures and intermittency in forced homogeneous isotropic turbulence based on large eddy simulation database. Using wavelet decomposition in one dimension and two dimension, it is found that polymer additives behave inhibitive effect on the intermittent pulse and the amount of coherent structures in forced homogeneous isotropic turbulence. The reconstructions of velocity waveform for coherent structures with strongest intermittence were surveyed at the scale a = 2 6 obtained by maximum energy criterion, showing that the quasi-periodicity and intermittence for coherent structures in polymer solutions are not as distinct as that in the Newtonian fluid. To detect intermittency, the flatness factor and local intermittency measure for velocity fluctuation signals were calculated by wavelet coefficients. The results for flatness factor in one-dimensional wavelet transform and LIM in both one-dimensional and twodimensional wavelet transform intuitively show that the local contribution to intermittency in polymer solutions flow is relatively smaller, leading to the suppression of intermittency in forced homogeneous isotropic turbulence with polymer additives. The robustness of wavelet transform method has been demonstrated in exploring the characteristics of turbulent structures and intermittency, which are of key importance in understanding the mechanism of turbulent drag reduction.

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“…Moreover, modeling approaches for viscoelastic turbulent flows have to be developed and these are essentially of RANS (Reynolds-averaged Navier-Stokes) techniques and of LES (large-eddy simulation). DNS studies on these issues are ongoing (Kawamoto et al, 2010;Pinho et al, 2008;Tsukahara et al, 2011c) and the observations in these works will be valuable for those studying such complicated flows using RANS and LES.…”

Section: Resultsmentioning

confidence: 99%