If the stream function ψ=3x2−y3, what is the magnitude of velocity at point (2,2)?
∴∂ψ∂x=6xand∂ψ∂y=−3y2 Butu=−∂ψ∂y
=−(−3y2)=3×22=12
v=∂ψ∂x=6x=6×2=12
∴ Resultant velocity =√u2+v2
=√(12)2+(12)2=√288 = 16.97 = 7