Suppose I have a cylinder of gas and at time t=0 I can turn on a strong vertical gravitational force. Let the force change quickly (but a time long compared the mean free path divided by the average gas particle velocity) to reach some constant maximum value F(z,t) = F_max. (This force can be approximately produced by putting the cylinder in a centrifuge that rapidly spins up to some max RPM.) Can I argue that for very strong force F_max the gas in the upper half of the cylinder will expand and the gas in the lower half of the tube will compress so that there should initially be a temperature difference between the gas in top and the bottom of the cylinder? Is this in effect part of the physics behind the Ranque-Hilsch vortex tube? Thanks for any help!