Eventos Anais de eventos
ENCIT 2018
Brazilian Congress of Thermal Sciences and Engineering
INFLUENCE OF CURVATURE VARIATIONS ON THE SECONDARY INSTABILITIES
Submission Author:
Larissa Marques , SP , Brazil
Co-Authors:
Larissa Marques, Josuel Kruppa Rogenski, Leandro Franco de Souza
Presenter: Leandro Franco de Souza
doi://10.26678/ABCM.ENCIT2018.CIT18-0677
Abstract
The centrifugal instability mechanism of boundary layers over concave surfaces is responsible for the development of counter-rotating vortices aligned in the streamwise direction known as Görtler vortices. Depending on various geometrical and flow conditions, these vortices in its nonlinear form can significantly distort the baseline flow and lead to secondary instabilities. These disturbances can develop into horseshoe vortices or a sinuous motion of the Görtler vortices, known as even (varicose) and odd (sinuous) modes, respectively. Direct numerical simulations have been performed using a high-order, pseudo-spectral numerical code (Hope) to investigate the influence of the curvature variations on the secondary instabilities. Considering a surface with variable curvature and a concave plate of constant radius, one spanwise wavelengths were disturbed in all numerical tests, to compare the development of this vortice on two different geometries. A comparison between results obtained was performed by analyzing the evolution of non stationary disturbances in a base-flow represented by Görtler vortices. The results introducing disturbances that give rise to odd and even modes simultaneously show that, for the spanwise wavelength analyzed, the variation in radius of curvature has a strong influence on these amplitude.
Keywords
direct numerical simulation, Görtler vortices, secondary instabilities, curvature variations
