Lx = 48h, Ly = 16.8h and Lz = 2h
Bottom plate is stationary and roughness is added to it
Top plate moves with a velocity Uw
Roughness height (r) = 0.2h
Pitch separation (s) = 5r and 10r
Spanwise vorticity showing the KH structures behind the ribs
The KH structures are absent due to the short pitch separation