**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**31575

##### DNS of a Laminar Separation Bubble

**Authors:**
N. K. Singh,
S. Sarkar

**Abstract:**

Direct numerical simulation (DNS) is used to study the evolution of a boundary layer that was laminar initially followed by separation and then reattachment owing to generation of turbulence. This creates a closed region of recirculation, known as the laminar-separation bubble. The present simulation emulates the flow environment encountered in a modern LP turbine blade, where a laminar separation bubble may occur on the suction surface. The unsteady, incompressible three-dimensional (3-D) Navier-Stokes (NS) equations have been solved over a flat plate in the Cartesian coordinates. The adverse pressure gradient, which causes the flow to separate, is created by a boundary condition. The separated shear layer undergoes transition through appearance of ╬ø vortices, stretching of these create longitudinal streaks. Breakdown of the streaks into small and irregular structures makes the flow turbulent downstream.

**Keywords:**
Adverse pressure gradient,
direct numerical simulation,
laminar separation bubble.

**Digital Object Identifier (DOI):**
doi.org/10.5281/zenodo.1077223

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