Energy Amplification of Streamwise Constant Channel Flow Over Riblets
نویسنده
چکیده
Riblets have been used as a passive method of reducing the drag of a fluid flowing over an airfoil. Riblets are structures that run parallel to one another that are positioned longitudinally to the flow. It has been shown experimentally that the drag coefficients over the surface can be reduced by up to 10% when the shape, spacing and height of the riblets are optimized. However, the mechanism of drag reduction is not fully understood. This paper investigates the effects of riblets on energy amplification in streamwise constant channel flow. The linearized Navier-Stokes equations are described by the two-dimensional/three-component model. The irregular domain is converted into a uniform one through a change of coordinates. Spectral methods are used to discretize these equations, leading to a finite-dimensional state space model. The transient growth and H2 norm of the flow system are calculated, which shows that the presence of riblets can reduce the transient growth and H2 norm of channel flow.
منابع مشابه
Drag reduction by riblets.
The interaction of the overlying turbulent flow with riblets, and its impact on their drag reduction properties are analysed. In the so-called viscous regime of vanishing riblet spacing, the drag reduction is proportional to the riblet size, but for larger riblets the proportionality breaks down, and the drag reduction eventually becomes an increase. It is found that the groove cross section A(...
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