Large eddy simulations in curved square ducts: Variation of the curvature radius

Cécile Munch (1) , Olivier Métais (1)

1 LEGI - Laboratoire des Écoulements Géophysiques et Industriels [Grenoble]

We present large-eddy simulations of the turbulent compressible flow at a low Mach number in curved ducts. The aim is to investigate the influence of the curvature radius R c on the flow. Three simulations are carried out at R c = 3.5 D h , 6.5 D h and 10.5 D h (D h hydraulic diameter). We first validate our computations by comparison with the incompressible experiments performed by Chang et al. (1983, Turbulent flow in a strongly curved U-bend and downstream tangent of square cross-sections. Physico-chemical Hydrodynamics, 4(3), 243–269). We observe that the decrease of the curvature radius is accompanied by a strong intensification of the secondary transverse flows : a rise of 100% of the maximum of their intensity is obtained between the smaller and the higher values of R c . We show that the secondary flows strength is directly related to the radial pressure gradient intensity. We observe a significant modification of the near-wall laws in the vicinity of each curved walls in correlation with the favourable or the adverse streamwise pressure gradient depending on the nature of the curvature. The influence of R c on the coherent vortices is also estimated.

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Cécile Munch, Olivier Métais. Large eddy simulations in curved square ducts: Variation of the curvature radius. Journal of Turbulence, 2007, 8 (28), pp.1-18. ⟨10.1080/14685240601142859⟩. ⟨hal-00270832⟩