$(10$ pts$)$ Answer the following questions about the concept of circulation.

a$.$ Write down the Kelvin Circulation Theorem.

b$.$ In the boundary layer of a flow where viscous effects are important, the circulation around a closed

curve is $2\frac{m^2}{s}$ at time $t.$ Can we conclude that the circulation around the same closed curve will

remain $2\frac{m^2}{s}$ at time $t+t?$ Explain your reasoning.