Lecture 27: Flow at high Reynolds numbers (Boundary layer theory)
Blausius has proposed an approximate solution to the above equation for the flow near the solid surface. From the solution, , the gradient at or near the surface may be calculated
to obtain drag
(Fig. 27a)
For the flow over a flat plate, the local shear stress has been calculated as
where,
Defining drag coefficient, , where is the drag on the plate (or any solid surface) and ‘A’ is the plate-area, is calculated as
, the gradient 
at or near the surface may be calculated 
, where 
is the drag on the plate (or any solid surface) and ‘A’ is the plate-area, 
is calculated as 
