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**Harvard**

Javadi, A. och Nilsson, H. (2014) *A comparative study of scale-adaptive and large-eddy simulations of highly swirling turbulent flow through an abrupt expansion*.

** BibTeX **

@conference{

Javadi2014,

author={Javadi, Ardalan and Nilsson, Håkan},

title={A comparative study of scale-adaptive and large-eddy simulations of highly swirling turbulent flow through an abrupt expansion},

booktitle={27th IAHR Symposium on Hydraulic Machinery and Systems, Montreal, Canada},

pages={Art. no. 022017},

abstract={The strongly swirling turbulent flow through an abrupt expansion is investigated using highly resolved LES and SAS, to shed more light on the stagnation region and the helical vortex breakdown. The vortex breakdown in an abrupt expansion resembles the so-called vortex rope occurring in hydro power draft tubes. It is known that the large-scale helical vortex structures can be captured by regular RANS turbulence models. However, the spurious suppression of the small-scale structures should be avoided using less diffusive methods. The present work compares LES and SAS results with the experimental measurement of Dellenback et al. (1988). The computations are conducted using a general non-orthogonal finite-volume method with a fully collocated storage available in the OpenFOAM-2.1.x CFD code. The dynamics of the flow is studied at two Reynolds numbers, Re=6.0×104 and Re=105 , at the almost constant high swirl numbers of Sr=1.16 and Sr=1.23, respectively. The time-averaged velocity and pressure fields and the root mean square of the velocity fluctuations, are captured and investigated qualitatively. The flow with the lower Reynolds number gives a much weaker outburst although the frequency of the structures seems to be constant for the plateau swirl number.},

year={2014},

}

** RefWorks **

RT Conference Proceedings

SR Electronic

ID 203006

A1 Javadi, Ardalan

A1 Nilsson, Håkan

T1 A comparative study of scale-adaptive and large-eddy simulations of highly swirling turbulent flow through an abrupt expansion

YR 2014

T2 27th IAHR Symposium on Hydraulic Machinery and Systems, Montreal, Canada

AB The strongly swirling turbulent flow through an abrupt expansion is investigated using highly resolved LES and SAS, to shed more light on the stagnation region and the helical vortex breakdown. The vortex breakdown in an abrupt expansion resembles the so-called vortex rope occurring in hydro power draft tubes. It is known that the large-scale helical vortex structures can be captured by regular RANS turbulence models. However, the spurious suppression of the small-scale structures should be avoided using less diffusive methods. The present work compares LES and SAS results with the experimental measurement of Dellenback et al. (1988). The computations are conducted using a general non-orthogonal finite-volume method with a fully collocated storage available in the OpenFOAM-2.1.x CFD code. The dynamics of the flow is studied at two Reynolds numbers, Re=6.0×104 and Re=105 , at the almost constant high swirl numbers of Sr=1.16 and Sr=1.23, respectively. The time-averaged velocity and pressure fields and the root mean square of the velocity fluctuations, are captured and investigated qualitatively. The flow with the lower Reynolds number gives a much weaker outburst although the frequency of the structures seems to be constant for the plateau swirl number.

LA eng

DO 10.1088/1755-1315/22/2/022017

LK http://dx.doi.org/10.1088/1755-1315/22/2/022017

LK http://publications.lib.chalmers.se/records/fulltext/203006/local_203006.pdf

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