Viscoelastic jet instabilities studied by direct numerical simulations

• Tipo: Artigo em Revista Científica Internacional
• Data: 2023

Autores

M. C. Guimarães (Autor) Outra; F. T. Pinho (Autor) FEUP; C. B. da Silva (Autor) Outra

Revista

Título: Physical Review Fluids

Vol. 8

Página Inicial: 103301

Editora: American Physical Society

Indexação

ISI Web of Knowledge - 1 Citação

Scopus - 1 Citação

Outras Informações

ID Authenticus: P-00Z-AD8

DOI: 10.1103/physrevfluids.8.103301

Abstract (EN): Direct numerical simulations of spatially evolving submerged jets with viscoelastic FENE-P fluids at high Reynolds numbers are performed to investigate the development of inertioelastic shear-layer and jet-column instabilities. An analysis of the flow structures, mean and fluctuating velocities, and spectra of perturbation energy at several positions of the flow shows that viscoelasticity has a destabilizing effect at the linear region of perturbation growth but a stabilizing effect at the nonlinear regime. At the linear regime, shorter waves are destabilized first and as the Weissenberg number Wi is increased this effect is propagated towards longer waves until most modes become more unstable. The frequency domain of instability is increased by a factor larger than four for the jet at the highest Wi. At the nonlinear regime, thin sheets of highly stretched polymers at the shearlayer region lead to a suppression of the local velocity gradient and to the formation of additional inflection points in the base flow velocity profile. This is accompanied by lower rates of perturbation growth and a decrease of the characteristic Strouhal number of the jet column mode at the end of the potential core by a factor of 1.8 for the highest Wi jet. The physical mechanisms that explain the observed phenomena are offered but the need for a nonlinear stability theory that also accounts for nonparallel base flow effects is highlighted.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 34