[vickrenz]

hi everyone...
i am doing simulation of so2 dispersion from single stack using fluent (3 dimension). i used 3 models: energy, viscous (spalart-allmaras), and species transport(with no reaction). i used natural convection too. i used 2 materials in my case, so2 and air. mass fractions of so2 in mass flow inlet(stack) is 1 and mass fractions of air in velocity inlet is 1. and the properties of mixture-template (density, Cp, thermal conductivity,etc..) i set default. is it right???

when i running my case, i got convergence problem, especially when i include natural convection (gravitational acceleration, operating temperature,etc..). i try running with 1st order and its convergence. when i used 2nd order its not convergence. after the set up, fluent shows me the folowing Turbulent viscosity Limited to viscosity Ratio.... . i have decreased URF, increased the limit of turb. viscosity ratio and smooth the grid to solve this problem but it doesn't work.
could anybody tell me why does this happen please????

thank you so much

vickrenz

[Allan Walsh]

I'm pretty sure you don't want to set the mass fractions of both SO2 and air at 1, if I understand your set-up. The mass fractions should sum to 1.