Influence of Pressure Gradients on the Evolution of the Görtler Instability

Rogenski, Josuel Kruppa; Souza, Leandro Franco de; Floryan, J. M.

doi:10.2514/1.j054658

Cited by 8 publications

(6 citation statements)

References 12 publications

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“…This is one of the investigations proposed in the present paper. The present investigation tries to clarify the effect of pressure gradient on the fastest growing mode in order to justify the stronger instability of the large spanwise wavenumber vortices in a favorable pressure gradient, confirm the explanation offered by Rogenski et al (2016a) based on the size of the vortices, thickness of the shear layer and velocity gradients. Rogenski et al (2016a) also considered cases where the pressure gradient went from adverse to favorable and from favorable to adverse.…”

Section: Introductionsupporting

confidence: 80%

“…The present investigation tries to clarify the effect of pressure gradient on the fastest growing mode in order to justify the stronger instability of the large spanwise wavenumber vortices in a favorable pressure gradient, confirm the explanation offered by Rogenski et al (2016a) based on the size of the vortices, thickness of the shear layer and velocity gradients. Rogenski et al (2016a) also considered cases where the pressure gradient went from adverse to favorable and from favorable to adverse. Again, by considering the same three distinct values of spanwise wavenumbers, they show that vortices with different spanwise wavelength respond differently to pressure gradient, but regardless of the wavelength, going from favorable to adverse pressure gradient results in greater instability than going from adverse to favorable pressure gradient.…”

Section: Introductionsupporting

confidence: 80%

“…The results for the nonlinear development and saturation of Görtler vortices obtained by Matsson (2008) can be compared with the results obtained by Souza and his group (Rogenski et al 2013;2016a;2016b), who have been using direct numerical simulation (DNS) to study the development of Görtler vortices in boundary layers with pressure gradient. In a first paper Rogenski et al (2013) studied the effect of curvature variation on the nonlinear development of Görtler vortices as a way to control their growth and consequent transition to turbulence.…”

Section: Introductionmentioning

confidence: 84%

“…In a second paper Rogenski et al (2016a) address the question of variable pressure gradient, with more details about the free stream condition than that given by Mangalam et al (1985). A zero pressure gradient boundary layer was used as reference condition and three conditions were studied, constant pressure gradient, constant Hartree parameter and linear varying pressure gradient.…”

Section: Introductionmentioning

confidence: 99%

“…According to Rogenski et al (2016a), the effect of pressure gradient depends on the vortices spanwise wavenumbers. By considering three different values of spanwise wavenumber they observed that large spanwise wavenumbers are more unstable when the pressure gradient is favorable.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Pressure Gradient on the Development of Görtler Vortices

Fernandes

Mendonça

2019

J.Aerosp. Technol. Manag.

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Boundary layers over concave surfaces may become unstable due to centrifugal instability that manifests itself as stationary streamwise counter rotating vortices. The centrifugal instability mechanism in boundary layers has been extensively studied and there is a large number of publications addressing different aspects of this problem. The results on the effect of pressure gradient show that favorable pressure gradients are stabilizing and adverse pressure gradient enhances the instability. The objective of the present investigation is to complement those works, looking particularly at the effect of pressure gradient on the stability diagram and on the determination of the spanwise wave number corresponding to the fastest growth. This study is based on the classic linear stability theory, where the parallel boundary layer approximation is assumed. Therefore, results are valid for Görtler numbers above 7, the lower limit where local mode linear stability analysis was identified in the literature as valid. For the base flow given by the Falkner-Skan solution, the linear stability equations are solved by a shooting method where the eigenvalues are the Görtler number, the spanwise wavenumber and the growth rate. The results show stabilization due to favorable pressure gradient as the constant amplification rate curves are displaced to higher Görtler numbers, with the opposite effect for adverse pressure gradient. Results previously unavailable in the literature identifying the fastest growing mode spanwise wavelength for a range of Falkner-Skan acceleration parameters are presented.

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Section: Introductionsupporting

confidence: 80%

Section: Introductionsupporting

confidence: 80%