Question

Use the sub navigation below to navigate within this series of questions. Water at 20°C is flowing with velocity of 1.01 m/s between two parallel flat plates placed 1 cm apart. Given: The properties of water at 20°C are p = 998.0 kg/m3, u = 1.002 * 10-3kg/m-s and Pr = 7.01 7. value 4.00 points Required information You received credit for this question in a previous attempt Determine the distance from the entrance at which the velocity boundary layers meet. (Round the final answer to one decimal place.) The distance from the entrance at which the velocity boundary layers meet is 1.0432 m.

Answer 1

Given u = 1.01 m/s p = 998 kg/m3 u = 1.002 x 10-3 kg/ms Pr = 7.01 Distance between the plate, h = 1 cm = 0.01 m The boundary layer will meet when 8 = 8 h 0.01 = 0.005 m 2 2 II Assuming the flow is laminar, velocity boundary layer thickness is given by 8 4.91 Vup/ux (1) Or 8² uop 4.912 XA Substituting the known values X = 0.0052 x 1.01 X 998 = 1.0432 m 4.912 X 1.002 x 10-3 Similarly, for a laminar flow, thermal boundary layer thickness is given by 8. 4.91 Pr-1/3 μωρ/μα Or 82 ucp Pr2/3 X = 4.912 XA

Substituting the known values X= 0.0052 x 1.01 X 998 x 7.012/3 4.912 x 1.002 x 10-3 = 3.821 m Distance at which velocity boundary layers meet = 1.0432 m Distance at which thermal boundary layers meet = 3.821 m