In some wind tunnels, the test-section wall is porous or perforated; fluid is sucked out to provide a thin viscous boundary layer. the wall of the test section is 4 m long and contains 800 holes of 6-mm diameter per square meter of area. the suction velocity out each hole is vs = 10 m/s, and the test section entrance velocity is v1 = 45 m/s. assuming incompressible flow of air at 20c and 1 atm, compute (a) v0, (b) the total wall suction volume flow, (c) v2, and (d) vf.

During the experiment if you could triple the breakaway magnetic force with all other quantities left unchanged, what is the new value for the critical velocity if it was v0 (initial velocity), initially? (b) now if you halved the radius with all other quantities left unchanged, what is the new critical velocity if it was v0 (initial velocity), initially? (c) if during the experiment, critical velocity quadrupled with all other quantities left unchanged, what is the new breakaway force if its magnitude was initially f0,?