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On numerical simulations of turbulent flows subjected to system rotation
KTH, School of Engineering Sciences (SCI), Mechanics.
2016 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Different aspects of numerical simulations of turbulent flows are assessed by considering a fully-developed turbulent channel flow that is rotating in the spanwise direction. Differences between differential and explicit algebraic Reynolds-stress models (RSMs) are investigated theoretically and numerically. Simulation results are compared with existing DNS-data. Both families of RSMs are demonstrated to achieve good qualitative agreement with the DNS. The results constitutes a demonstration of the validity of the so called extended weak-equilibrium assumption for systems with a superimposed solid body rotation. An original derivation, based on sound physical grounds, of the extended weak-equilibrium assumption is presented. It is further examined if the roll-cell vortex pattern, that constitutes a secondary flow field, has an influence on the averaged solutions obtained by application of the Reynolds-Averaged Navier-Stokes equations. This is assessed by comparison of results obtained by either considering the secondary plane as homogeneous in the spanwise direction or by accounting for a fully three-dimensional flow field. Simulations demonstrate that existence of roll-cells in the latter case yields results that are in closer agreement with DNS-data compared with if they are suppressed as for the former case. Aspects of numerical treatment of explicit source terms are also assessed in the framework of finite volume methods for collocated grids.

Place, publisher, year, edition, pages
2016. , 65 p.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-194499OAI: oai:DiVA.org:kth-194499DiVA: diva2:1040715
Subject / course
Fluid Mechanics
Supervisors
Examiners
Available from: 2016-10-28 Created: 2016-10-28 Last updated: 2016-10-28Bibliographically approved

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