Normally aerodynamic drag is not modelled as a function of pressure. Typical parameters for aerodynamic drag are Mach number, Reynolds number and/or Knudsen number. There is interested in a deep atmospheric probe investigating the atmosphere of Neptune. It would be useful if this probe could descend to an atmospheric depth where the ambient pressure is 1000 bars. At pressures that great van der Waal forces come into play and the standard equation of state no longer applies. It seems reasonable to assume that drag coefficient would be significantly different at such extreme pressures. I've searched the web but came up empty about drag coefficient's dependence upon extreme pressure. Anyone out there know anything about this topic? Thanks!

Gary