Large Eddy Simulation of a Turbulent Wake behind a Body of Revolution at ReD = 5000

2019 ◽  
Author(s):  
Fengrui Zhang ◽  
Yulia T. Peet
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Wake ◽  
Body Of Revolution ◽  
Eddy Simulation ◽  
Large Eddy

Large-eddy simulation of flow over an axisymmetric body of revolution

2018 ◽  
Vol 853 ◽  
pp. 537-563 ◽  
Author(s):  
Praveen Kumar ◽  
Krishnan Mahesh
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Large Eddy Simulation ◽  
Axisymmetric Body ◽  
The Body ◽  
Computational Domain ◽  
Body Of Revolution ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Self Similar

Wall-resolved large-eddy simulation (LES) is used to simulate flow over an axisymmetric body of revolution at a Reynolds number, $Re=1.1\times 10^{6}$, based on the free-stream velocity and the length of the body. The geometry used in the present work is an idealized submarine hull (DARPA SUBOFF without appendages) at zero angle of pitch and yaw. The computational domain is chosen to avoid confinement effects and capture the wake up to fifteen diameters downstream of the body. The unstructured computational grid is designed to capture the fine near-wall flow structures as well as the wake evolution. LES results show good agreement with the available experimental data. The axisymmetric turbulent boundary layer has higher skin friction and higher radial decay of turbulence away from the wall, compared to a planar turbulent boundary layer under similar conditions. The mean streamwise velocity exhibits self-similarity, but the turbulent intensities are not self-similar over the length of the simulated wake, consistent with previous studies reported in the literature. The axisymmetric wake shifts from high-$Re$ to low-$Re$ equilibrium self-similar solutions, which were only observed for axisymmetric wakes of bluff bodies in the past.

Large eddy simulation of the gas??particle turbulent wake flow

2004 ◽  
Vol 5 (1) ◽  
pp. 106-110
Author(s):  
Kun Luo ◽  
Han-hui Jin ◽  
Jian-ren Fan ◽  
Ke-fa Cen
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Wake ◽  
Wake Flow ◽  
Eddy Simulation ◽  
Large Eddy

Large-eddy simulation of temporally developing double helical vortices

2019 ◽  
Vol 863 ◽  
pp. 79-113 ◽  
Author(s):  
J.-B. Chapelier ◽  
B. Wasistho ◽  
C. Scalo
Keyword(s):  
Growth Rate ◽  
Large Eddy Simulation ◽  
Vortex Core ◽  
Large Scale ◽  
Axial Direction ◽  
Turbulent Wake ◽  
Eddy Simulation ◽  
Vortex Reconnection ◽  
Helical Vortices ◽  
Large Eddy

This paper investigates the transient regime and turbulent wake characteristics of temporally developing double helical vortices via high-fidelity large-eddy simulation (LES) for circulation Reynolds numbers in the range $Re_{\unicode[STIX]{x1D6E4}}=7000{-}70\,000$, vortex-core radii between $r_{c}=0.06R$ and $0.2R$ and helical pitches in the range $h=0.36R{-}0.61R$, where $R$ is the initial helix radius. The present study achieves three objectives: (i) assess the influence of $Re_{\unicode[STIX]{x1D6E4}}$, $r_{c}$ and $h$ on the growth rates of the helical vortex instability driven by mutual inductance; (ii) characterize the type of vortex reconnection events that appear during transition; (iii) study the characteristics of turbulence in the far wake, and in particular quantify the anisotropy in the flow. The initial transient dynamics is conveniently described in terms of the non-dimensional time $t^{\star }=t\unicode[STIX]{x1D6E4}/h^{2}$, yielding the dimensionless growth rate of $\unicode[STIX]{x1D6FC}^{\ast }\sim 20$ and collapsing of all the LES data for a given $r_{c}/h$ ratio. The vortex-core displacement growth rate is found to be Reynolds-number independent, and decreases for larger $r_{c}/h$ ratios. Several vortex reconnection events are identified during the transition, mostly initiated by the leap frogging of helical vortices. This phenomenon causes the entanglement of orthogonal vortex filaments, leading to their separation, followed by the creation of elongated threads in the axial direction. The turbulent wake generated by the breakdown of the helical vortices is found to be highly anisotropic with the axial fluctuations being dominant compared to the radial and azimuthal fluctuations (near one-dimensional turbulence). The study of integral length scales shows the presence of a strong large-scale anisotropy, retaining the memory of the initial helical pitch $h$, in particular for the integral scale in the axial direction. The large-scale anisotropy is propagated through the inertial and dissipative ranges, determined from the computation of the moments of velocity gradients in the three directions.

Large Eddy Simulation of Turbulent Wake Behind a Square Cylinder With a Nearby Wall

2001 ◽  
Vol 124 (1) ◽  
pp. 81-90 ◽  
Author(s):  
Tong-Miin Liou ◽  
Shih-Hui Chen ◽  
Po-Wen Hwang
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Stokes Equations ◽  
Turbulent Wake ◽  
Wake Flow ◽  
Square Cylinder ◽  
Free Standing ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Large Eddy

Computations of the time-averaged and phase-averaged fluid flow and heat transfer based on large eddy simulation (LES) are presented for turbulent flows past a square cylinder with and without a nearby wall at a fixed Reynolds number of 2.2×104. The finite-volume technique was used to solve the time-dependent filtered compressible Navier-Stokes equations with a dynamic subgrid-scale turbulence model, and the numerical fluxes were computed using alternating in time the second-order, explicit MacCormack’s and the modified Godunov’s scheme. Results show some improvements in predicting the streamwise evolutions of the long-time-averaged streamwise mean velocity and total fluctuation intensity along the centerline over those predicted by using Reynolds stress models. A better overall centerline streamwise mean velocity distribution is also predicted by the present LES than by other LES. The wall proximity effect is studied through the comparison of turbulent wake flow past one free standing cylinder and one with a nearby wall, and is illustrated by the phase-averaged spanwise vorticity components and the vortex celerity of spanwise vortices. Moreover, documentation is given on the mechanisms responsible for the augmentation of heat transfer through the spanwise and longitudinal vortices as well as periodic and random fluctuations.

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