Drag coefficient : The effect of skin friction/wall shear stress is to retard the free stream flow. It is quantified by skin friction coefficient at a particular x -location on the flat plate and is expressed by Eq. (5.9.20). When this parameter is integrated over the entire length of the plate, then total drag coefficient is obtained (Fig. 5.9.5). In terms of free stream parameter and wall shear stress, is quantified as follows;

(5.9.22)

Comparing Eqs (5.9.18 & 5.9.22), it is seen that skin friction drag coefficient for a flat plate is directly proportional to the values of evaluated at the trailing edge of the plate.

(5.9.23)

 

Fig. 5.9.5: Variation of skin friction coefficient along the length of a flat plate.