ay2014ce2134液压4tq平板上边界层.pdfVIP

CE2134 Hydraulics AY2014 Tutorial 4 Boundary layer over flat te National University of Singapore Department of Civil Environmental Engineering CE2134 Hydraulics Academic Year 2014 Tutorial 4 QA Question #3 to be discussed. Question #2 to be submitted by 3rd Nov 2013 Question 1. Show that, if a flat te with sides a, b in length, is towed through a fluid so that the boundary layer is entirely laminar, the ratio of towing speeds so that the drag remains constant regardless of whether a or b is in the flow direction is given by U a 3 a / b U b where U a is the stream if side a is in the flow direction and Ub is the corresponding fluid velocity if b is in the flow direction. [Douglas et al] Question 2 Find the shear stress and the thickness of the boundary layer at the centre and the trailing edge of a smooth flat te 3.0 m wide and 0.6 m long parallel to the flow, immersed in 0 15 C water flowing at an undisturbed velocity of 0.1 m/s. Assume a laminar boundary layer over the whole te and the parabolic velocity profile. Question 3 A flat te 8 m long and 0.5 m wide is towed at 8 m/s through water. Determ he total drag on the te. Assume the boundary layer changes from laminar to turbulent at a Reynolds number of 300,000. Question 4 Same problem as #3. Plot the thickness of the boundary layer and the local shear stress distribution along the te. CE2134 AY2014 4 平板上的边界层新加坡国立大学土木与环境工程系 CE2134 2014 学年 4 问答待讨论的问题 #3。问题 #2 将于 2013 年 11 月 3 日之前提交问题 1. 表明，如果将边长为 a、b 的平板拖过流体，使边界层完全层流，则无论 a 或 b 是否在流体中，拖曳速度之比都使拖曳力保持