One equation model for turbulent channel flow with second order viscoelastic corrections.

• Type: Article in International Scientific Journal
• Date: 2008

Authors

F. T. Pinho (Author) FEUP; B. Sadanandan (Author) Other; R. Sureshkumar (Author) Other

Journal

Title: Flow, Turbulence and Combustion

Vol. 81

Pages: 337-367

ISSN: 1386-6184

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 10 Citations

ISI Web of Science

Scopus - 10 Citations

COMPENDEX

INSPEC

Scientific classification

FOS: Engineering and technology > Chemical engineering

CORDIS: Technological sciences > Engineering > Chemical engineering

Other information

Authenticus ID: P-003-VRP

DOI: 10.1007/s10494-008-9134-6

Abstract (EN): A modified second order viscoelastic constitutive equation is used to derive a k– l type turbulence closure to qualitatively assess the effects of elastic stresses on fully-developed channel flow. Specifically, the second order correction to the Newtonian constitutive equation gives rise to a new term in the momentum equation involving the time-averaged elastic shear stress and in the turbulent kinetic energy transport equation quantifying the interaction between the fluctuating elastic stress and rate of strain tensors, denoted by Pw, for which a closure is developed and tested. This closure is based on arguments of isotropic turbulence and equilibrium in boundary layer flows and a prioriPw could be either positive or negative. When Pw is positive, it acts to reduce the production of turbulent kinetic energy and the turbulence model predictions qualitatively agree with direct numerical simulation (DNS) results obtained for more realistic viscoelastic fluid models with memory which exhibit drag reduction. In contrast, Pw<0 leads to a drag increase and numerical breakdown of the model occurs at very low values of the Deborah number, which signifies the ratio of elastic to viscous stresses. Limitations of the turbulence model primarily stem from the inadequacy of the k–l formulation rather than from the closure for Pw. An alternative closure for Pw, mimicking the viscoelastic stress work predicted by DNS using the Finitely Extensible Nonlinear Elastic-Peterlin fluid model, which is mostly characterized by Pw>0 but has also a small region of negative Pw in the buffer layer, was also successfully tested. This second model for Pw leads to predictions of drag reduction, in spite of the enhancement of turbulence production very close to the wall, but the equilibrium conditions in the inertial sub-layer were not strictly maintained.

Language: English

Type (Professor's evaluation): Scientific