Numerical Simulation on Laminar-Turbulent Transition of the Channel Flow with Simulated Wall Roughness

1995 ◽  
pp. 245-252
Author(s):  
Kiyoshi Yamamoto
Keyword(s):  
Numerical Simulation ◽  
Channel Flow ◽  
Wall Roughness ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

Constrained large-eddy simulation of laminar-turbulent transition in channel flow

2014 ◽  
Vol 26 (9) ◽  
pp. 095103 ◽  
Author(s):  
Yaomin Zhao ◽  
Zhenhua Xia ◽  
Yipeng Shi ◽  
Zuoli Xiao ◽  
Shiyi Chen
Keyword(s):  
Large Eddy Simulation ◽  
Channel Flow ◽  
Eddy Simulation ◽  
Turbulent Transition ◽  
Large Eddy ◽  
Laminar Turbulent Transition

DIRECT NUMERICAL SIMULATION OF LAMINAR–TURBULENT TRANSITION AT SUPERSONIC FLOW OVER A SHARP FLAT PLATE

2018 ◽  
Vol 49 (5) ◽  
pp. 495-505 ◽  
Author(s):  
Ivan Vladimirovich Egorov ◽  
Alexander Vitalyevich Fedorov ◽  
Quan Hoang Dihn
Keyword(s):  
Numerical Simulation ◽  
Supersonic Flow ◽  
Direct Numerical Simulation ◽  
Flat Plate ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

scholarly journals Laminar–turbulent transition in channel flow with superhydrophobic surfaces modelled as a partial slip wall

2019 ◽  
Vol 881 ◽  
pp. 462-497 ◽  
Author(s):  
Francesco Picella ◽  
J.-Ch. Robinet ◽  
S. Cherubini
Keyword(s):  
Channel Flow ◽  
Initial Conditions ◽  
Slip Length ◽  
Low Noise ◽  
Superhydrophobic Surfaces ◽  
Partial Slip ◽  
Turbulent Transition ◽  
Onset Of Turbulence ◽  
Fully Developed Turbulent Flow ◽  
Laminar Turbulent Transition

Superhydrophobic surfaces are capable of trapping gas pockets within the micro-roughnesses on their surfaces when submerged in a liquid, with the overall effect of lubricating the flow on top of them. These bio-inspired surfaces have proven to be capable of dramatically reducing skin friction of the overlying flow in both laminar and turbulent regimes. However, their effect in transitional conditions, in which the flow evolution strongly depends on the initial conditions, has still not been deeply investigated. In this work the influence of superhydrophobic surfaces on several scenarios of laminar–turbulent transition in channel flow is studied by means of direct numerical simulations. A single phase incompressible flow has been considered and the effect of the micro-structured superhydrophobic surfaces has been modelled imposing a slip condition with given slip length at both walls. The evolution from laminar, to transitional, to fully developed turbulent flow has been followed starting from several different initial conditions. When modal disturbances issued from linear stability analyses are used for perturbing the laminar flow, as in supercritical conditions or in the classical K-type transition scenario, superhydrophobic surfaces are able to delay or even avoid the onset of turbulence, leading to a considerable drag reduction. Whereas, when transition is triggered by non-modal mechanisms, as in the optimal or uncontrolled transition scenarios, which are currently observed in noisy environments, these surfaces are totally ineffective for controlling transition. Superhydrophobic surfaces can thus be considered effective for delaying transition only in low-noise environments, where transition is triggered mostly by modal mechanisms.

Validation of the PTM Transition Model on a 3D Flow Through a Turbine Cascade

2016 ◽  
Author(s):  
Sergiy Yershov ◽  
Viktor Yakovlev
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Numerical Results ◽  
Transitional Flow ◽  
Turbine Cascade ◽  
Production Term ◽  
Flow Acceleration ◽  
Turbulent Transition ◽  
Displacement Thickness ◽  
Laminar Turbulent Transition

This study presents a numerical simulation of a 3D viscous subsonic flow in the VKI-Genoa turbine cascade taking into account the laminar-turbulent transition. The numerical simulation is performed using the Reynolds-averaged Navier-Stokes (RANS) equations and the low-Reynolds k-ω SST turbulence model. The Langtry’s algebraic Production Term Modification (PTM) model is applied for modeling the laminar-turbulent transition. The governing equations are integrated using the second-order accurate Godunov’s type implicit ENO scheme. Computations of both fully turbulent and transitional flows are carried out. Much attention is given to the comparison between the present numerical results and the existing experimental data. The comparison was based on the surface distributions of the isentropic velocity, the friction velocity, the flow acceleration parameter, the displacement thickness, the shape-factor, and the momentum thickness Reynolds number. Velocity profiles upstream and downstream of the transition onset were compared also. The numerical results obtained show an influence of the transition on the secondary flow pattern. In the case of the transitional flow, when compared with the fully turbulence flow case, the endwall boundary layer cross-flow starts upstream, and it is more intensive, but less massive due to a thinner boundary layer in the laminar flow region.

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