An experimental study of the influence of riblets on transition

1996 ◽  
Vol 315 ◽  
pp. 31-49 ◽  
Author(s):  
G. R. Grek ◽  
V. V. Kozlov ◽  
S. V. Titarenko
Keyword(s):  
Experimental Study ◽  
Three Dimensional ◽  
Negative Influence ◽  
Positive Influence ◽  
Linear Stage ◽  
Turbulent Transition ◽  
Transition Structures ◽  
Stage Transition ◽  
Tollmien Schlichting ◽  
Laminar Turbulent Transition

An experimental study of the effect of riblets on three-dimensional nonlinear structures, the so-called Λ-vortices on laminar-turbulent transition showed that riblets delay the transformation of the Λ-vortices into turbulent spots and shift the point of transition downstream. This result is opposite to the negative influence of such ribbed surfaces on two-dimensional linear Tollmien-Schlichting waves (the linear stage of transition). Thus, the ribbed surface influences laminar-turbulent transition structures differently: a negative influence on the linear-stage transition structures and a positive influence on the nonlinear-stage transition structures. It is demonstrated that transition control by means of riblets requires special attention to be paid to the choice of their location, taking into account the stage of transition.

scholarly journals Experimental study of the laminar-turbulent transition on models of wings with subsonic and supersonic leading edge at M = 2

2019 ◽  
Vol 1404 ◽  
pp. 012097 ◽  
Author(s):  
N V Semionov ◽  
Yu G Yermolaev ◽  
A D Kosinov ◽  
V L Kocharin ◽  
A V Panina ◽  
...  
Keyword(s):  
Experimental Study ◽  
Leading Edge ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

On the Effects of Turbulence Modeling on the Fluid-Structure Interaction of a Rigid Cylinder

2016 ◽  
Author(s):  
Guilherme Feitosa Rosetti ◽  
Guilherme Vaz ◽  
André Luís Condino Fujarra
Keyword(s):  
Turbulence Modeling ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Boundary Layer Separation ◽  
Turbulent Transition ◽  
Moving Cylinder ◽  
Wide Range ◽  
Cylinder Flow ◽  
Laminar Turbulent Transition

The cylinder flow is a canonical problem for Computational Fluid Dynamics (CFD), as it can display several of the most relevant issues for a wide class of flows, such as boundary layer separation, vortex shedding, flow instabilities, laminar-turbulent transition and others. Several applications also display these features justifying the amount of energy invested in studying this problem in a wide range of Reynolds numbers. The Unsteady Reynolds Averaged Navier Stokes (URANS) equations combined with simplifying assumptions for turbulence have been shown inappropriate for the captive cylinder flow in an important range of Reynolds numbers. For that reason, recent improvements in turbulence modeling has been one of the most important lines of research within that issue, aiming at better prediction of flow and loads, mainly targeting the three-dimensional effects and laminar-turbulent transition, which are so important for blunt bodies. In contrast, a much smaller amount of work is observed concerning the investigation of turbulent effects when the cylinder moves with driven or free motions. Evidently, larger understanding of the contribution of turbulence in those situations can lead to more precise mathematical and numerical modeling of the flow around a moving cylinder. In this paper, we present CFD calculations in a range of moderate Reynolds numbers with different turbulence models and considering a cylinder in captive condition, in driven and in free motions. The results corroborate an intuitive notion that the inertial effects indeed play very important role in determining loads and motions. The flow also seems to adapt to the motions in such a way that vortices are more correlated and less influenced by turbulence effects. Due to good comparison of the numerical and experimental results for the moving-cylinder cases, it is observed that the choice of turbulence model for driven and free motions calculations is markedly less decisive than for the captive cylinder case.

Coupling PSE and FLUENT to Predict Laminar-Turbulent Transition in Boundary Layers

2013 ◽  
Vol 432 ◽  
pp. 168-172
Author(s):  
Y. Zhou ◽  
Y.H. Fang
Keyword(s):  
Flat Plate ◽  
Boundary Layers ◽  
Three Dimensional ◽  
Basic Flow ◽  
Two Dimensional ◽  
S Wave ◽  
S Waves ◽  
Turbulent Transition ◽  
Transition Criterion ◽  
Laminar Turbulent Transition

In this paper, the coupling method of PSE and FLUENT was experimented for predicting the laminar-turbulent transition. The software FLUENT was used to get the basic flow over a flat plate. A two-dimensional T-S wave and a pair of three-dimensional T-S waves were fed in at the entrance. The transition criterion was verified by DNS results. The availability of the coupling methodology has been evaluated.

Experimental study of the influence of external disturbances on the position of the laminar-turbulent transition on swept wings at M = 2

2021 ◽  
Vol 28 (3) ◽  
pp. 319-325
Author(s):  
Yu. G. Ermolaev ◽  
A. D. Kosinov ◽  
V. L. Kocharin ◽  
A. N. Semenov ◽  
N. V. Semionov ◽  
...  
Keyword(s):  
Experimental Study ◽  
External Disturbances ◽  
Turbulent Transition ◽  
Swept Wings ◽  
Laminar Turbulent Transition
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