In my seminars I talk about the three magic formulas you need to know if you want to understand how centrifugal pumps function. As the velocity of a liquid increases, the pressure, ninety degrees to the flow, will decrease, and as the velocity of a liquid decreases the pressure, ninety degrees to the flow will increase.
Pressure acting on an area creates a force.
Velocity times area must remain a constant if liquid is to flow. It all started when the Wright brothers discovered the correct wing shape for an aircraft. Look at the following diagram. You will note that the air is flowing under the wing at some velocity. The air going over the top of the wing has a longer path to travel, so its velocity must increase if it is to join with the air coming underneath the wing.