Turbulent planar wakes of viscoelastic fluids analysed by direct numerical simulations

• Type: Article in International Scientific Journal
• Date: 2022

Authors

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

Journal

Title: Journal of Fluid Mechanics

Vol. 946

Initial page: A26

ISSN: 0022-1120

Publisher: Cambridge University Press

Indexing

ISI Web of Knowledge - 0 Citations

Scopus

Other information

Authenticus ID: P-00X-2FC

DOI: 10.1017/jfm.2022.559

Abstract (EN): Direct numerical simulations employing the finitely extensible nonlinear elastic constitutive model closed with Peterlin's approximation (FENE-P) are used to investigate the far-field region of turbulent planar wakes of viscoelastic fluids and to develop the theory describing these flows. The theoretical results display excellent agreement with the simulations and provide new scaling laws for the evolution of the shear layer thickness delta(x) similar to x(1/2), mean velocity deficit Delta U(x) similar to x(-1/2) and, for very high Deborah numbers, of the maximum polymer shear stresses sigma([p])(c) (x) similar to x(-2) and averaged polymer chain extension tr((C) over bar (x) - I) similar to x(-2), where x is the streamwise distance from the solid body generating the wake. The theory is able to show the existence of self-similarity for the profiles of mean velocity, mean polymer shear stress, averaged polymer chain extension and the conditions for similarity of the turbulent shear stress, and is very well supported by the numerical simulations. Similarly to the case of viscoelastic turbulent planar jets (Guimaraes et al., J. Fluid Mech., vol. 899, 2020, p. A11), when the inlet Weissenberg and Deborah numbers are sufficiently large, turbulent viscoelastic wakes exhibit a considerable reduction of the spreading rate and of the normalised Reynolds stresses. However, for very large downstream locations the turbulent viscoelastic wake recovers the classical evolution laws observed for Newtonian turbulent planar wakes.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 36