Journal
FLOW TURBULENCE AND COMBUSTION
Volume 71, Issue 1-4, Pages 311-331Publisher
KLUWER ACADEMIC PUBL
DOI: 10.1023/B:APPL.0000014917.71180.f1
Keywords
boundary layer separation; DNS; incompressible flow; transition
Categories
Ask authors/readers for more resources
A three-dimensional Direct Numerical Simulation (DNS) of a laminar separation bubble in the presence of oscillating flow is performed. The oscillating flow induces a streamwise pressure gradient varying in time. The special shape of the upper boundary of the computational domain, together with the oscillating pressure gradient causes the boundary layer flow to alternately separate and re-attach. When the inflow decelerates, the shear layer starts to separate and rolls up. Simultaneously the flow becomes 3D. After a transient period, the phase-averaged reverse flow inside the separation bubble reaches speeds ranging from 20 up to 150% of the free-stream velocity. During these phases, the flow is absolutely unstable and self-sustained turbulence can exist. When the inflow starts to accelerate, a spanwise roll of turbulent flow is shed from the shear layer. Shortly after this, the remainder of the separation bubble moves downstream and rejoins with the shed turbulent roll. During the flow-acceleration phase, a patch of laminar boundary layer flow is obtained. Along the flat plate, a series of turbulent patches of flow travelling downstream, separated by laminar flow can be observed, reminiscent of boundary layer flow in a turbine cascade with periodically appearing free-stream disturbances.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available