Fabrizio Rama PhD Student

hi everyone, I'm working with FEFLOW 7.1 using a Richard's equation on a 3D model.
I would like to simulate a spill of pure ethanol in the vadose zone (170Lt in a source volume about 0.5 m[sup]3[/sup]) with compound's transport in both, vadose and saturated zone, but I'm facing with different problems:
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[li]FEFLOW formulation of variable density flow (White Paper Vol.1 Chapter 7 and 17, White Paper Vol.2 Chapter 1) seems to focus only on salt-water density where the incresing of concentration involves increasing in density. But in my case the density ratio would be negative (-0.211, considering common ethanol and water density), and I don't understand which max concentration (Cs) I have to apply in Problem settings -->Transport settings-->References values. If I apply a negative (not phisically based) concentration just to follow the FEFLOW density estimation based on concentration, the model crashed. If I apply the pure ethanol concentration (I supposed 789000 mg/lt, being the ethanol density 0.789 g/cm[sup]3[/sup]) it doesn't work either. [/li]
[li]I changed the viscosity to "variable-dependent on solute concentration" as you can see in attached fig. But using this relationship, I can't obtain the real pure ethanol dynamic viscosity of 1.24 cP in the source. Obtained viscosity is much more higher.[/li]
[li]I don't understand what the option "Flow field direction" in Problem settings -->Transport settings-->General settings implies. I activate "reverse flow field applied to mass transport problems", but I didn't sort any effect on the plumes of contaminant.[/li]
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Thanking in advance for any help.