A large eddy simulation of an airfoil turbulent wake subjected to streamwise curvature

2008 ◽  
Vol 56 (8) ◽  
pp. 1233-1240 ◽  
Author(s):  
E. Farsimadan ◽  
M. R. Mokhtarzadeh-Dehghan
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Wake ◽  
Eddy Simulation ◽  
Large Eddy

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.

Large-eddy simulation and experimental study on the turbulent wake flow characteristics of a two-bladed wind turbine

2017 ◽  
Vol 60 (12) ◽  
pp. 1861-1869 ◽  
Author(s):  
Kun Luo ◽  
RenYu Yuan ◽  
XueQing Dong ◽  
JianWen Wang ◽  
SanXia Zhang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Large Eddy Simulation ◽  
Wind Turbine ◽  
Flow Characteristics ◽  
Turbulent Wake ◽  
Wake Flow ◽  
Eddy Simulation ◽  
Large Eddy
Sign in / Sign up

Export Citation Format

Share Document