Thermodynamics of single-phase one-dimensional fluid flow

Fluid flow processes in helium within the range 4-10 K and 10-100 N cm ^-2 pressure are similar to those of ordinary fluids near their critical points. Three thermodynamic parameters, the Gruneisen parameter, isentropic compressibility, and velocity of sound, which are weakly non-catalytic near the critical point, are used to describe fluid flow processes in fluids in the near critical range. It is found that if temperature is not used as a variable in fluid state equation, flow profiles can be easily evaluated in a single-phase fluid region, including close to or transecting the transposed critical line.