Fluid Compressibility of with density and molar volume :

c_f = \frac{1}{\rho_f} \frac{\partial \rho_f}{\partial p} = -\frac{1}{V_{mf}} \frac{\partial V_{mf}}{\partial p}

The multi-phase compressibility is a linear sum of compressibilities of its phases.

Approximations

Incompressible fluid

c_f(p) = 0

Slightly compressible fluid

c_f(p) = \rm const

Ideal gas

c_f(p) = \frac{1}{p}

Wide range compressibility proxy model

c_f(p) = \frac{c_0}{1+c_0 \cdot p}

See also

[Compressibility] [Multi-phase compressibility]