Spatial direct numerical simulations based on the full incompressible unsteady Navier-Stokes equations are employed to explore the microscale effects of suction holes on an accelerated 3-D laminar boundary layer. For a single row of holes the influence of the hole diameter and the volume flow rate per hole is investigated. It turns out that the receptivity of the flow to the induced crossflow vortices is distinctly larger than the receptivity of the desired stabilizing 2-D mean-flow distortion. Oversuction triggering turbulence occurs at lower suction rates than in 2-D base flows. For an array of holes partial cancellation of upstream induced crossflow vortices can be achieved by an appropriate order of downstream hole rows.
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