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Conference on Turbulence and Interactions TI2006 May June Porquerolles France

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Niveau: Supérieur, Doctorat, Bac+8
Conference on Turbulence and Interactions TI2006, May 29 - June 2, 2006, Porquerolles, France DNS of a Turbulent Channel Flow with Streamwise Rotation at Different Reynolds Numbers T. Weller?, M. Oberlack? ?Fluid Dynamics Group, Technische Universitat Darmstadt, Petersenstraße 13, D-64287 Darmstadt, Germany ABSTRACT In this work a turbulent channel flow rotating about the streamwise direction is presented. The theory is based on the investigations of [3] employing the symmetry group theory. It was found that a cross flow in the spanwise direction is induced. Statistical evaluations have shown that all six components of the Reynolds stress tensor are non-zero. A series of direct numerical simulations (DNS) has been conducted at rotation number Ro=20 for different Reynolds numbers. In this paper the results of the DNS are presented and discussed. INTRODUCTION Rotating turbulent flows play more a major role in engineering applications such as in gas turbine blade passages, pumps and rotating heat exchang- ers to name only a few. In these cases secondary flows are induced caused by centrifugal or Cori- olis forces. Investigations of [3] using symme- try theory showed that there is a new turbulent scaling law related to the turbulent channel flow rotating about the mean flow direction. Figure 1 depicts the flow geometry. x1 x2 x3 ?1 u1 u3 Fig.

  • ferent reynolds

  • reynolds numbers

  • channel flow

  • streamwise mean

  • show also

  • turbulent channel

  • all computation

  • both streamwise

  • finalized all


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Conference on Turbulence and Interactions TI2006, May 29  June 2, 2006, Porquerolles, France
DNS of a Turbulent Channel Flow with Streamwise Rotation at Different Reynolds Numbers
∗ ∗ T. Weller , M. Oberlack Fluid Dynamics Group, Technische Universität Darmstadt, Petersenstraße 13, D64287 Darmstadt, Germany
ABSTRACT In this work a turbulent channel flow rotating about the streamwise direction is presented. The theory is based on the investigations of [3] employing the symmetry group theory. It was found that a cross flow in the spanwise direction is induced. Statistical evaluations have shown that all six components of the Reynolds stress tensor are nonzero. A series of direct numerical simulations (DNS) has been conducted at rotation number Ro=20 for different Reynolds numbers. In this paper the results of the DNS are presented and discussed.
INTRODUCTION
Rotating turbulent flows play more a major role in engineering applications such as in gas turbine blade passages, pumps and rotating heat exchang ers to name only a few. In these cases secondary flows are induced caused by centrifugal or Cori olis forces. Investigations of [3] using symme try theory showed that there is a new turbulent scaling law related to the turbulent channel flow rotating about the mean flow direction. Figure 1 depicts the flow geometry.
W 1
x 3
x 2
u 1
u3
x 1
Fig. 1. Sketch of the flow geometry of a turbulent channel flow rotating about the mean flow direction
The flow has several common features with the classical rotating channel flow rotating about the spanwise direction [1] but also has some different characteristics. The induction of a mean velocity inx3direction [4] is the most obvious difference compared to the classical case. This cross flow
can be deduced by investigating the mean mo mentum equation and the Reynolds stress trans port equation. Statistical evaluations have shown that all six components of the Reynolds stress tensor are nonzero.
Both the predicted cross flow and the nonzero components of the Reynolds stress tensor could be verified in a DNS at Reynolds number Re=180 for different rotation rates [5]. In this paper the re sults of a DNS at rotation rate Ro=20 at three dif ferent Reynolds numbers (Re=180, 270 and 560) are presented and discussed. The main objective of the present paper is to analyze these effects at different Reynolds numbers.
DIRECTNUMERICALSIMULATION
Numerical Method and Computations
The numerical technique which was chosen is a standard spectral method with Fourier decompo sition in streamwise and spanwise direction as well as Chebyshev decomposition in wallnormal direction. The numerical code for channel flow was developed at KTH/Stockholm [2]. Addi tional features such as the streamwise rotation and statistics were added during the project. All flow quantities are nondimensionalized byh/2 anduclwherehis the channel width anducl