Viscoelastic jet instabilities studied by direct numerical simulations

• Type: Article in International Scientific Journal
• Date: 2023

Authors

M. C. Guimarães (Author) Other; F. T. Pinho (Author) FEUP; C. B. da Silva (Author) Other

Journal

Title: Physical Review Fluids

Vol. 8

Initial page: 103301

Publisher: American Physical Society

Indexing

ISI Web of Knowledge - 1 Citation

Scopus - 1 Citation

Other information

Authenticus ID: 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.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 34