Inscrição na biblioteca: Guest
TSFP DL Home Arquivos Comitê executivo

THE EFFECT OF FIBERS ON TURBULENT QUANTITIES IN BACKWARD FACING STEP CHANNEL FLOW: MEASUREMENTS AND NUMERICAL SIMULATIONS

Kati J. Lindroos
Mechanical Pulping Lines, Metso Paper Valkeakoski Oy PO Box 125, FIN-37601 Valkeakoski, Finland

Mika V. Piirto
Department of Energy and Process Engineering, Tampere University of Technology PO Box 589, FIN-33101 Tampere, Finland

Juha-Pekka T. Huhtanen
Department of Energy and Process Engineering, Tampere University of Technology PO Box 589, FIN-33101 Tampere, Finland

Resumo

This paper introduces a comparison between CFD simulations and experimental data of a dilute fibre suspension of bleached softwood chemical pulp fibres in a backward facing step channel flow. Average velocities and turbulence quantities are measured with Particle Image Velocimetry (PIV) technique in pure water and in 0.2 mass-% suspension flow, and the results are compared with numerically modelled data. Different mechanisms of the modification of turbulence are studied and, based on a theoretical review, an extra dissipation term is added to Reynolds stress turbulence model (RSM) to simulate the effect of fibres on turbulent quantities. The attenuation of turbulence in the step area and the shift of reattachment point further downstream after abrupt expansion is well captured by the presented model.