The hydraulic capacitance (also called the compliance) tells us how hard it is to change the pressure of a fluid stored by adding more of the fluid to the tank. It is the factor relating the rate of change of volume to the rate of change of capacitive pressure (difference). It is equal to the inverse of the elastance.

C_V

[C_V] = m^3/Pa

compliance

hydraulic capacitive characteristic, hydraulic capacitance-pressure relation, elastance, (general) capacitance

For a range with constant capacitance, C_V = const., we have

   ∆V = C_V·∆p_C

If the pressure of the fluid is the result of gravity, the hydraulic capacitance of the container depends upon the cross section of the tank:

   C_V = A(h)/(rho·g)

hydraulische Kapazität