3. During a test on a circular duct 2m in diameter, it was found that the air velocity is zero at the duct surface and 6m/s on the axis of the duct when the flow rate was 9m/s. Assuming that the velocity distribution to be given by u = c-cr" where u is the fluid velocity at any radius r, determine the values of the constants C1, C2 and n, specifying the units of C1 and C2. Is the flow laminar or turbulent? [6m/s; 6m -0.825/s; 1.825; turbulent; Problem 4.13 Douglas et al Fluid Mechanics]