Question

au ar +0 ay au dy? Revie ди ar + =0 ду Water flows past a flat plate of length L = 15 cm at U = 2 m/s. What is the disturbance thickness of the boundary layer at = 10 cm from the front of the plate? The properties of water are pw = 1000 kg/m” and Vw = 1x10-6 m/s Express your answer in mm to three significant figures. View Available Hint(s) 8 = 1.12 mm Submit Previous Answers where x is the distance from the leading edge. The solution to these equations can be expression in the form ý = f ( VRez). This was first done numerically by Paul Blasius, and the resulting curve is known as the Blasius solution for the laminar boundary layer. Using these results, the disturbance thickness, displacement thickness, momentum thickness, and local shear stress can all be expressed as functions of the position along the plate S 5.0 Disturbance thickness Rez 8* = 1.721 Displacement thickness Rez 0.664 Momentum thickness Rez Shear stress To = 0.332u (1) Re, -2 Correct 2 Part B - Boundary layer drag The plate in Part A is b = 80 cm wide in the direction perpendicular to the flow. What is the drag force on one side of the plate? Express your answer in N to three significant figures. View Available Hint(s) The total drag on the plate is Fpz = Cppbl (pU), where 1.328 Cof= is the drag coefficient. For the purpose of this Rel tutorial, we will assume that the flow remains laminar as long as Re <5(105) IVO AEDIT vec ? Figure 1 of 1 > For= 14.3 N d d2 Submit Previous Answers U X Incorrect; Try Again; 5 attempts remaining А В P Pearson

(Re_x)_cr=5(10^5)

Answer 1

Part-B Given data :- Length of plate, L = 15cm = 0.15m Width of plate, b Flow velocity, U= 2m/s For water, Iw=2000 8oom = 0.8m -6 ma's kg/m3, Vw = 10 Total drag on the plate is given by- For = Cofob. L(90²) where 1-328 Cof= Rew 4 U.L Rela amis x 0.15m 10-6 m²/s 3x105 < 5x10 So, 1.328 2.4246 XI0 X10-3 Cof 3x105 :: FF = 2.4246 X10 X 0.880.15 x Looo x 2 FDF = 1.1638 N -39 = l-ey Y = 1mm 2 part-c for a given velocity profile & Displacement thickness, S*= f (1-4) dy

- 39 S*- (1- 1+e (1-lte 7)dy - 39 s e о 1 *, је“, [s] - [+] : Бет - - - - -о 2 11 3xo Зе Х S' = 0. 333 mm