.. _oil_den_inv_lin_sec: Oil Inverse Linear Density model ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The inverse linear density model requires the input of a reference density, pressure and temperature, and compressibility and expansion coefficients. See example below: :: EOS OIL FORMULA_WEIGHT 508.0d0 DENSITY INVERSE_LINEAR REFERENCE_VALUE 995.98d0 !den0 [kg/m3] PRES_REF_VALUE 1.13d5 !p0 [Pa] TEMP_REF_VALUE 21.d0 !T0 [°C] COMPRESS_COEFF 5.63d-10 !cp [1/Pa] THERMAL_EXPANSION_COEFF 8.480d-4 !ct [1/°C] END ENTHALPY LINEAR_TEMP 1.d3 !c oil [J/kg/°C] VISCOSITY CONSTANT 3.0d-3 ![Pa.s] END The mathematical expression of the model is reported below: .. math:: \rho( p ,T )= \frac{\rho_0}{ [1−c_p ( p−p_0 )] [1+c_T (T −T_0 )]} where: .. math:: \begin{split} & p &= \mbox{pressure [Pa]} \\ &T &= \mbox{temperature [°C]} \\ &\rho_0 &= \mbox{reference density [kg/m3]} \\ &p_0 &= \mbox{reference pressure [Pa]} \\ &T_0 &=\mbox{reference temperatures [°C]} \\ &C &=\mbox{compressibility coefficient [kg/m3/Pa]} \\ &E &=\mbox{thermal expansion coefficient [kg/m3/°C]} \end{split} Units cannot be specified, therefore values must be entered in the units prescribed above.