Choose the expression for the displacement thickness, δ+ of the boundary layer for flow over a flat plate
1
\({\delta ^ + } = \mathop \smallint \limits_0^\delta \left( {1 - \frac{u}{{{u_\infty }}}} \right)dy\)
2
\({\delta ^ + } = \mathop \smallint \limits_0^\delta \frac{u}{{{u_\infty }}}dy\)
3
\({\delta ^ + } = \mathop \smallint \limits_0^\delta \frac{u}{{{u_\infty }}}\left( {1 - \frac{u}{{{u_\infty }}}} \right)dy\)
4
\({\delta ^ + } = \mathop \smallint \limits_0^\delta {\left( {\frac{u}{{{u_\infty }}}} \right)^2}dy\)