I am tasked with calculating the force on the wall exerted by the fluid. The resultant force is equal to the rate of change of momentum and the force has a body force(gravity is assumed to be neglected so this is zero), a pressure force(force of wall on fluid).
I was wondering why the pressure force at the inlets out outlets as well as along the surface of the liquid are assumed to be zero and only the contribution of the wall is included here.
The explanation i have been given is that the pressure force is zero as the pressure at both the inlet and the outlets to the control volume are atmospheric but I am not sure how to interpret this.
For full details see pages 9 and 10 of this: https://learn.lboro.ac.uk/pluginfile.php/504744/mod_resource/content/1/Fluid_Mechanics_6.pdf