Etude dans les fluides à composants multiples et des structures dans les fluides non newtoniens

• Research unit: COST
• Project number: C97.0071

Key words (English)

Turbulence; Numerical Simulation; Non-Newtonian Fluids; FENE-P model; Dissipation Scales; Drag Reduction.

Research programs (English)

COST-Action P3 - Simulation of physical phenomena in technological application

Short description (English)

See abstract

Further information (English)

Full name of research-institution/enterprise: EPF Lausanne Département de génie mécanique Institut de machines hydrauliques et de mécanique des fluides IMHEF-LMF

Partners and International Organizations (English)

A, B, CH, CZ, D, DK, E, F, FIN, GR, H, IRL, NL, PL, Sl, UK

Abstract (English)

Non-Newtonian fluid behaviour is simulated by introducing a composite bead-spring model of mesomolecules in a Newtonian solvent. A FENE-P type of model is used. A first study looks at the normal stresses generated by these molecules when they float passively in simulated Newtonian turbulence. The method used for generating the turbulent fields was fully spectral thus having high small-scale accuracy. When the particles are released near the wall, the largest FENE-P stress generated is related to the ratio of the molecular (FENE) time scales to those of the local dissipation range of the flow. The FENE stress increases as the two scales become comparable. In the second part of the study, a plane channel direct simulation was carried out using a second order finite difference code. Here the FENE-P molecules are active in that their stress is used in the calculation of the simulated flow field. The effects of rather high numerical dissipation of the scheme become evident. The results indicate that in order to recover the drag-reducing properties of the dilute polymer chains in Newtonian turbulent flows, it is necessary to resolve the dissipation range scales near the walls.

References in databases (English)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C97.0071