Hi Transient is result of changing in momentum and momentum is result of changing in velocity. Velocity is a vector parameter. It means that Velocity's change is due to changing in velocity's quantity or velocity's direction. All discussions about transient Analysis speak about Transient as result of changing in AMOUNT of velocity not changing in DIRECTION of it. Assume a pipe with no operations or branches, valves or ... but there is a Tee along the pipe. Changing in velocity's direction makes momentum and therefore it makes a transient. Am I right or I make mistake and Transient is due to JUST velocity's quantity?