Direct Numerical Simulation of Turbulence with Scalar Transfer around Complex Geometries Using the Immersed Boundary Method and Fully Conservative Higher-Order Finite-Difference Schemes

Nagata, Kouji; Suzuki, Hiroki; Sakai, Yasuhiko; Hayase, Toshiyuki

doi:10.5772/12838

Cited by 7 publications

(2 citation statements)

References 32 publications

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“…. This is in agreement with pervious simulations (Nagata et al, 2010;Suzuki et al, 2013), ensuring the accuracy of the spatial resolution near the wall.…”

Section: Computational Mesh Systemsupporting

confidence: 91%

DNS study on the development of boundary layer with heat transfer under the effects of external and internal disturbances

Xia

Ito

Sakai

et al. 2014

JFST

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The effects of external and internal disturbances on the development of boundary layer with heat transfer are investigated by means of direct numerical simulation (DNS) based on the finite difference scheme. The fractional step method is used to solve the governing equations. The external disturbance is generated by a regular turbulence-generating grid, while the internal disturbance is generated by a tripping object mounted on the wall. In order to clarify the momentum and heat transfer mechanism in a boundary layer under these effects, the instantaneous and statistical characteristics of velocity and temperature fields are presented and discussed along with their interactions. The results show that the boundary layer in the case with grid turbulence becomes turbulent even though the Reynolds number based on the momentum thickness is low. On the other hand, in the case with the tripping object, only low-amplitude fluctuations are generated in the vicinity of the tripping object and the boundary layer does not fully developed. The grid increases the skin friction and enhances heat transfer more significantly than the tripping object. It is also found that strong strain in the viscous sublayer, which is induced by the vortical motion in the buffer layer, contributes to the enhancement of heat transfer.

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“…. This is in agreement with pervious simulations (Nagata et al, 2010;Suzuki et al, 2013), ensuring the accuracy of the spatial resolution near the wall.…”

Section: Computational Mesh Systemsupporting

confidence: 91%

DNS study on the development of boundary layer with heat transfer under the effects of external and internal disturbances

Xia

Ito

Sakai

et al. 2014

JFST

Self Cite

View full text Add to dashboard Cite

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“…When analysing incompressible flows, the energy conservation properties should be well held [4][5][6][7]. Previous studies have used an inviscid periodic flow to investigate the energy conservation properties of a flow field (e.g., [7]).…”

Section: Introductionmentioning

confidence: 99%

Multiscaled inviscid Taylor-Green vortex flow for examining energy conservation error in incompressible flows

Gong,

Suzuki,

Kouchi

2024

J. Phys.: Conf. Ser.

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This study investigates kinetic energy conservation errors in incompressible flows using multiplexed inviscid Taylor-Green vortices. Fourth-order precision Runge-Kutta methods, specifically five- and six-step methods, were employed and an inviscid two-dimensional periodic flow field was used as a test case. This method allows the energy conservation error to be suppressed to a very low level. Recent previous studies have dealt with turbulence generation using a multi-scale turbulence grid. In this study, the Taylor-Green vortex of the analytical solution is multiplexed to generate a flow field with a number of wavenumbers. Visualisation results of the initial field and the energy distribution over time were obtained. It was observed that the errors in the time evolution of the fluid energy were extremely small, and that the errors actually increased with time. However, the influence of the time step range was limited and the analytical and numerical solutions were in general agreement. As a result, it was confirmed that the inviscid Taylor-Green vortex is effective in examining the energy conservation error for incompressible flows.

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Turbulence structure and turbulence kinetic energy transport in multiscale/fractal-generated turbulence

Nagata¹,

Sakai²,

Inaba³

et al. 2013

Physics of Fluids

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The turbulence structure and turbulence kinetic energy transport in multiscale/fractal-generated turbulence in a wind tunnel are investigated. A low-blockage, space-filling square-type (i.e., fractal elements with square shapes) fractal grid is placed at the inlet of the test section. On the basis of the thickness of the biggest grid bar, t0, and the inflow velocity U∞, the Reynolds numbers (Re0) are set to 5900 and 11 400; these values are the same as those considered in previous experiments [D. Hurst and J. C. Vassilicos, “Scalings and decay of fractal-generated turbulence,” Phys. Fluids 19, 035103 (2007)10.1063/1.2676448; N. Mazellier and J. C. Vassilicos, “Turbulence without Richardson-Kolmogorov cascade,” Phys. Fluids 22, 075101 (2010)10.1063/1.3453708]. The turbulence characteristics are measured using hot-wire anemometry with I- and X-type probes. Generally, good agreements are observed despite the difference in the size of the test sections used: The longitudinal integral length-scale Lu and the Taylor microscale λ, and their ratio Lu/λ, are approximately constant during decay and are independent of the turbulent Reynolds number Reλ. Centerline statistical results support the finding of Mazellier and Vassilicos, namely, that the classical scaling of Lu/λ ∼ Reλ and the Richardson–Kolmogorov cascade are not universal to all boundary-free weakly sheared/strained turbulence. The cross-sectional profiles show that in the entire cross section of the tunnel, Lu/λ hardly changes in the decay region of the rms velocity, which implies that the turbulent field is self-similar. The production and transport of turbulence kinetic energy K in fractal grid turbulence are also investigated from cross-sectional profiles of the advection \documentclass[12pt]{minimal}\begin{document}${\cal A}^*$\end{document}A*, production \documentclass[12pt]{minimal}\begin{document}${\cal P}^*$\end{document}P*, triple-correlation transport \documentclass[12pt]{minimal}\begin{document}${\cal T}^*$\end{document}T*, pressure transport Π*, viscous diffusion \documentclass[12pt]{minimal}\begin{document}${\cal D}^*$\end{document}D*, and dissipation ɛ terms in the K transport equation. In the upstream region, turbulence produced by the biggest grid bar is transported to the central and outward regions by \documentclass[12pt]{minimal}\begin{document}${\cal T}^*$\end{document}T*. In the decay region, there is low turbulence production downstream of the interior of the biggest grid bar; turbulence energy in this region is mainly transported outward rather than toward the central region by \documentclass[12pt]{minimal}\begin{document}${\cal T}(=$\end{document}T(=\documentclass[12pt]{minimal}\begin{document}${\cal T}^*/\varepsilon )$\end{document}T*/ɛ). This characteristic of \documentclass[12pt]{minimal}\begin{document}${\cal T}$\end{document}T may cause a faster decay of K in the central region, as observed by Valente and Vassilicos [“The decay of turbulence generated by a class of multiscale grids,” J. Fluid Mech. 687, 300 (2011)10.1017/jfm.2011.353]. The advection term \documentclass[12pt]{minimal}\begin{document}${\cal A}^*$\end{document}A* is high and positive in the decay region, whereas Π* and \documentclass[12pt]{minimal}\begin{document}${\cal D}^*$\end{document}D* are low.

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Direct Numerical Simulation of Turbulence with Scalar Transfer around Complex Geometries Using the Immersed Boundary Method and Fully Conservative Higher-Order Finite-Difference Schemes

Cited by 7 publications

References 32 publications

DNS study on the development of boundary layer with heat transfer under the effects of external and internal disturbances

DNS study on the development of boundary layer with heat transfer under the effects of external and internal disturbances

Multiscaled inviscid Taylor-Green vortex flow for examining energy conservation error in incompressible flows

Turbulence structure and turbulence kinetic energy transport in multiscale/fractal-generated turbulence

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