Obtain an expression for the total force acting on a 180degr

Obtain an expression for the total force acting on a 180-degree U-bend in a horizontal pipe of circular cross section through which a viscous fluid is flowing at a constant rate. Explain any assumptions you make and reference your answer with an appropriately labelled diagram.

From the above given data total force can be calculated in the following manner

That is force = row* flow rate *(final velocity-initial velocity)