text: Flow rate q is given by\n\nq=AV\n\nwhere A is the cross sectional area of the pipe through which the fluid is flowing, and V is the velocity of the fluid in the pipe.\n\nIf you have a flow where the pipe diameter changes, conservation of flow states that\n\nA1V1=A2V2\n\nso if the pipe diameter decreases (and this the CSA gets smaller) the velocity of the fluid increases, and vice versa.