tanksufaceArea: This slot determines the surface area of the tank, and is required to determine the amount of pressure in the tank as the fluid level changes. The unit is m2.
gravity: This slot is the gravity constant assumed to be 9.8 m/s2. It is is also required to determine the amount of pressure in the tank as the fluid level changes.
fluidDensity: This is a slot of the fluid in the tank itself that is coupled with and assigned to the tank. It is required for the constraints that determine the amount of fluid pressure in the tank. The unit for this property is kg/m3.