Currently I am designing water machine that use atmospheric pressure to flow water from high level to lower level. The design look like a bigger scale model of continous ink system. The design is to help to flow water without overflow the lower level naturally.
I'm not sure what you are looking for. You can apply either uniform or non-uniform pressures to surfaces. For systems that aren't very tall, you can usually just use a uniform pressure. If the system is very tall, then you will have to apply non-uniform pressure to the faces with significant height.