Optimal Transient Growth in an Incompressible Flow past a Backward-Slanted Step

• Tipo: Artigo em Revista Científica Internacional
• Data: 2019

Autores

Afonso, MM (Autor) FCUP; Meliga, P (Autor) Outra; Serre, E (Autor) Outra

Revista

A Revista está pendente de validação pelos Serviços Administrativos.

Título: FLUIDS

Vol. 4

Página Final: 33

ISSN: 2311-5521

Indexação

ISI Web of Knowledge - 0 Citações

Scopus - 1 Citação

Outras Informações

ID Authenticus: P-00Q-DYG

DOI: 10.3390/fluids4010033

Abstract (EN): With the aim of providing a first step in the quest for a reduction of the aerodynamic drag on the rear-end of a car, we study the phenomena of separation and reattachment of an incompressible flow by focusing on a specific aerodynamic geometry, namely a backward-slanted step at 25 circle of inclination. The ensuing recirculation bubble provides the basis for an analytical and numerical investigation of streamwise-streak generation, lift-up effect, and turbulent-wake and Kelvin-Helmholtz instabilities. A linear stability analysis is performed, and an optimal control problem with a steady volumic forcing is tackled by means of a variational formulation, adjoint methods, penalization schemes, and an orthogonalization algorithm. Dealing with the transient growth of spanwise-periodic perturbations, and inspired by the need of physically-realizable disturbances, we finally provide a procedure attaining a kinetic-energy maximal gain on the order of 106, with respect to the power introduced by the external forcing.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 16