The effect of compressibility on the primary global instability of unforced laminar separation bubbles

Author(s)

Gennaro, E. M. ^[1] ; Souza, B. D. P. ^[1] ; Rodriguez, D. ^[2]

Affiliation

^[1] Sao Paulo State Univ UNESP, Campus Sao Joao da Boa Vista, BR-13876750 Sao Joao Da Boa Vista, SP - Brazil

^[2] Univ Politecn Madrid, ETSIAE UPM Sch Aeronaut, Plaza Cardenal Cisneros 3, E-28040 Madrid - Spain

• Document type: Review article
• Source: Journal of the Brazilian Society of Mechanical Sciences and Engineering; v. 41, n. 12 DEC 2019.
• Web of Science Citations: 0

Abstract

Laminar separation bubbles present a three-dimensional self-excited instability mechanism which leads to the appearance of spanwise-periodic structures. In incompressible flow, this mechanism was found to become active at conditions in which wave-like, two-dimensional perturbations are only convectively unstable. In the absence of continuous external excitation, the three-dimensional instability is expected to dominate the flow dynamics and initiate the laminar-turbulent transition. This work extends previous analyses by incorporating the effect of compressibility at subsonic conditions. Two-dimensional numerical simulations of a flat-plate boundary layer with a prescribed free-stream deceleration and acceleration are carried out to obtain a set of model laminar separation bubbles. A linear stability analysis is applied then, to study the influence of Reynolds and Mach numbers on the three-dimensional instability. (AU)

• FAPESP's process: 15/26759-9 - Global instability analysis of a compressible laminar separation bubble
• Grantee: Bruna Dias Pires de Souza
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 17/01586-0 - Instability of separated flows in aeronautical applications
• Grantee: Elmer Mateus Gennaro
• Support Opportunities: Regular Research Grants