Abstracts - KTH Mechanics

LES of a turbulent channel flow at streamwise rotation
N. A. Alkishriwi, M. Meinke, and W. Schröder ∗
In many engineering and industrial applications the investigations of rotating turbulent
flows is of great interest. In this type of flow the Coriolis force has a strong
influence on the turbulence. For instance, turbulent flows in a rotating channel are
severely affected by this force, which is induced by the system rotation. It produces
a secondary flow in the spanwise direction. Some research has been done for channel
flows with a spanwise rotation axis 1 . However, up to now very few investigations
have been done on channel flows with a rotation about the streamwise axis. Analyses
of this type of flow based on Lie-group theory and DNS 2 suggest that a secondary
flow perpendicular to the main flow direction is generated whose distribution strongly
depends on the rotational speed 3 . In the present study an LES of a turbulent streamwise
rotating channel flow at Reτ =180is performed using a moving grid method to
predict the three-dimensional structures and secondary flows. Among different issues
the impact of the formulation on the spanwise boundary condition is one of the major
objectives of this study. That is, the question whether or not periodic boundary
conditions in the spanwise direction allow to numerically reproduce the experiments
conducted by Recktenwald et al. will be addressed. The simulations are carried out
at rotation rates corresponding to Rossby numbers Ro = ub/Hf with H being half
the channel height Ro = ∞, Ro = 65.2, andRo = 37.5.
Results
First, the method of solution has been applied to compute the flow in a stationary
channel (Ro = ∞) atthesame Reynoldsnumber. The turbulent statistics and the
mean flow profiles are compared with the direct numerical simulations of Kim et al.
4 . Figure 1 shows the convincing comparison of the distribution of the LES based
streamwise, spanwise, and normal Reynolds stresses with DNS findings. The final
version of the study will focus on the detailed discussion of the flow field in the
streamwise rotating channel. A first result of the averaged spanwise velocity profile
is shown also in fig. 1.
∗Institute of Aerodynamics, RWTH Aachen University, Wüllnerstraße 5 thr. 7, D-52062 Aachen,
Germany.
1Kristofferson and Andersson, J. Fluid Mech 256, 163 (1993).
2Oberlack et al., Proceedings of the Center for turbulence Summer Programm 221 (1998).
3Recktenwald et al., Proc. of the Tenth European Turbulence Conf., Trondheim, Norway 2004.
4Kim et al., J. Fluid Mech 177, 133 (1987).
σ(v’’)/u τ σ(w’’)/uτ σ(u’’)/uτ
3.5
3
2.5
2
1.5
1
0.5
DNS KMM
LES at Ro = ∞
0
0 50 100
y
150 200
+
u 3
0.04
0.02
0
-0.02
-0.04
-1 -0.5 0
y
Ro. = 65.2
0.5 1
Figure 1: Distribution of the streamwise, spanwise, and normal Reynolds stresses
(left), spanwise velocity distribution (right).
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