I have a problem of gas(inert) stirring in ladle containing steel (alloy elements are mixed in steel) where in I have to study the effects of gas flow velocity on mixing of alloy elements in steel.Can anyone guide me how I can proceed as I found from literature that these type of problems are solved using VOF model.I could not get any literature .Please give me some information on VOF model

i think that VOF is not appropiate for your problem, because the VOF model is appropriate for stratified or free-surface flows, however it is not appropriate for flows in which the phases mix or separate. moreover, The VOF formulation relies on the fact that two or more phases are not interpenetrating. instead you use the eulerian model in which you can model granular flow accurately. you can get all the literature you want from the fluent user's and tutorial guide.