[sheintz]

Hello,
I'm trying to simulation a injection spray of diesel in a chamber, also I have a transcient time domain, lagrangian multi-phase model (Reitz breakup and Huh atomization).
I have a problem of "negative densities", and I would like to solve this problem with a change of the relaxation factors of the pressure, of the density (and maybe of the temperature). But I can change the value of the relation factor (in Analysis Controls>Solution Controls>Equation Behavior>Primary Values, in the Solver Parameters Panel),why ? (the values are in grey).
Why can not I change this relaxation factors ?
Some help would be greatly appreciated.
Kind regards
Simon