Turbulent channel flow of dense suspensions of neutrally buoyant spheres
2015 (English)In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 764, 463-487 p.Article in journal (Refereed) Published
Dense particle suspensions are widely encountered in many applications and in environmental flows. While many previous studies investigate their rheological properties in laminar flows, little is known on the behaviour of these suspensions in the turbulent/inertial regime. The present study aims to fill this gap by investigating the turbulent flow of a Newtonian fluid laden with solid neutrally-buoyant spheres at relatively high volume fractions in a plane channel. Direct numerical simulation (DNS) are performed in the range of volume fractions Phi=0-0.2 with an immersed boundary method (IBM) used to account for the dispersed phase. The results show that the mean velocity profiles are significantly altered by the presence of a solid phase with a decrease of the von Karman constant in the log-law. The overall drag is found to increase with the volume fraction, more than one would expect if just considering the increase of the system viscosity due to the presence of the particles. At the highest volume fraction investigated here, Phi = 0.2, the velocity fluctuation intensities and the Reynolds shear stress are found to decrease. The analysis of the mean momentum balance shows that the particle-induced stresses govern the dynamics at high Phi and are the main responsible of the overall drag increase. In the dense limit, we therefore find a decrease of the turbulence activity and a growth of the particle induced stress, where the latter dominates for the Reynolds numbers considered here.
Place, publisher, year, edition, pages
2015. Vol. 764, 463-487 p.
multiphase and particle-laden flows, suspensions, turbulent flows
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-160374DOI: 10.1017/jfm.2014.704ISI: 000348128700024ScopusID: 2-s2.0-84927127633OAI: oai:DiVA.org:kth-160374DiVA: diva2:791206
FunderEU, European Research Council, ERC-2013-CoG-616186
QC 201502272015-02-272015-02-192015-02-27Bibliographically approved