GATE Civil Engineering (CE) 2020 Shift 2 Solved Paper

Velocity distribution in a boundary layer is given by $\frac{\mathit{u}}{{\mathit{U}}_{\mathit{\infty }}}=\sin \left(\frac{\mathit{\pi }}{2}\frac{\mathit{y}}{8}\right)$, where $\mathit{u}$ is the velocity at vertical coordinate $\mathit{y},{\mathit{U}}_{\mathit{\infty }}$ is the free stream velocity and $\mathit{\delta }$ is the boundary layer thickness. The values of ${\mathit{U}}_{\mathit{\infty }}$ and $\mathit{\delta }$ are $0.3\mathit{m}∕\mathit{s}$ and $1.0\mathit{m}$, respectively. The velocity gradient $\left(\frac{\partial \mathit{u}}{\partial \mathit{y}}\right)$ (in ${\mathit{s}}^{-1}$, round off to two decimal places) at $\mathit{y}=0$, is__________.