Air speed after it passes a tunnel

[Alpha_42]

Hey guys, i am new to this subject and need some help. The idea is that in area AxB there is a constant airspeed of for example 6 m/s. I would like a formula or another way I can calculate the airspeed at area ExB. I hope you guys can help me out. Thanks.

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[rolotomassi]

I cannot be certain what your exact problem is, but for fluid flow near a boundary layer, Navier-Stokes equations can be used. Some good worked examples and a far better description of how to apply the NS equation can be found in 'Elemetary Fluid Dynamics' by D.J. Acheson