Modelling the new stress for improved drag reduction predictions of viscoelastic pipe flow

• Type: Article in International Scientific Journal
• Date: 2004

Authors

D. O. A. Cruz (Author) Other; Fernando T. Pinho (Author) FEUP; P. R. Resende (Author) Other

Journal

Title: Journal of Non-Newtonian Fluid Mechanics

Vol. 121 No. 2-3

Pages: 127-141

ISSN: 0377-0257

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 27 Citations

ISI Web of Science

Scopus - 34 Citations

Other information

Authenticus ID: P-000-8ZG

DOI: 10.1016/j.jnnfm.2004.05.004

Abstract (EN): A model is proposed for the new stress term in the momentum equation of a modified generalised Newtonian fluid that is used to mimic viscoelastic effects of fluids exhibiting drag reduction in turbulent pipe flow. The new stress quantifies the cross-correlation between the fluctuating viscosity and the fluctuating rate of strain and had been neglected in the k-epsilon low Reynolds number model originally developed by Cruz and Pinho [J. Non-Newt. Fluid Mechanics 114 (2003) 109]. With the inclusion of this new stress, the predictions of turbulent kinetic energy (k+) in drag reducing pipe flow are significantly improved at the cost of a slight deterioration in the prediction of other quantities for some of the fluids. The value of the coefficient C in the original model of Cruz and Pinho was also modified to correct a mistake and this was shown to improve the predictions for all fluids except for the solution of 0.125% PAA used to calibrate the model. Comparison of predictions with DNS results for a FENE-P model showed large overprediction of drag reduction and emphasize the need for improvements in extensional rheometry.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 15