For an ideal gas, this function is independent of pressure (although pressure remains as a valid input).
function c_v
extends Modelica.Icons.Function;
input Q.TemperatureAbsolute T = 298.15*U.K "Temperature" annotation(
Dialog(__Dymola_label = "<html><i>T</i></html>"));
input Q.PressureAbsolute p = p0 "Pressure" annotation(
Dialog(__Dymola_label = "<html><i>p</i></html>"));
output Q.CapacityThermalSpecific c_v "Isochoric specific heat capacity" annotation(
Dialog(__Dymola_label = "<html><i>c<sub>v</sub></i></html>"));
end c_v;