### 1.4.5. Density and Specific Heat Dependencies

For a pure substance, the flow solver allows only density and specific heat capacity to be functions of temperature or pressure.

When you select the `Value` option for density or specific heat capacity, you can use an expression to specify Density and/or Specific Heat Capacity, but the expression is allowed to depend only on pressure and temperature for liquids and gases. For a solid, they can depend on temperature or spatial location (x, y, z), but not both at the same time.

For ideal gases, the density is evaluated using the Ideal Gas law and the specific heat may be a function of temperature only.

If density, specific heat, or other properties are set as expressions that depend on pressure, the solver automatically uses the absolute pressure when evaluating the expression.

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