[vinaynitrkl]

I am calculating O2 mass transfer across gas-liquid. (air and deaerated water)
2D mesh, mesh size=0.01m, ht=3.2m, b=0.172m
*Segregated Unsteady solver
*Mixture model: 2 phase with slip vel and imp. body force
*k-eps realizable model
*Species transport model
*2 mass transfer mechs :Forward and back : Mechanism constant rate(is it ok?)
*gas vel = 0.1 m/s, water vel. =0.03m/s
*O2 mass frac. (liq)= 0.4*e-6
*O2 mass frac (air)=.23
*time step=0.01
*Rest default


Result: reversed flow in 2 faces on pressure-outlet 3.
And 0.098 as mass fractn of O2 in liq. where fluidization hasn't even started.
Help!