Question

Boundary layer separation takes place when

(a) $\left ( \frac{du}{dy} \right )_{y=0}=$ +ve value

(b) $\left ( \frac{du}{dy} \right )_{y=0}=$ - ve value

(c) $\left ( \frac{du}{dy} \right )_{y=\delta}=$ 0

(d) $\left ( \frac{du}{dy} \right )_{y=0}=$ 0