Final answer:
Surging is the movement of the liquid in partially filled tanks, characterized by an irregular and unsteady flow.
Step-by-step explanation:
The movement of the liquid in partially filled tanks is called surging. When a liquid is partially filled in a tank and the tank experiences an irregular and unsteady flow of the liquid, it is referred to as surging. This phenomenon can occur due to various reasons such as changes in the flow rate or sudden pressure changes.