transport equation for SGS scalar variance
 

Dear Friend, I got one doubt at transport equation for SGS scalar variance, in the literature i found two slight different equation for the variance. 1. Subgrid scale variance and dissipation of a scalar field in LES by C.Jimenez, F,Ducros et al vol 13, phsics of fluids ,2001, 1748 to 1754 2. Subgrid -Scale modeling for Turbulent reacting flows by Andrew W.cook and James J.Riley Combustion and Flame 112,593-606 (1998) in the above two papers , there is transport equation for SGS scalar variance, but both r differed by two terms, i could not able to understand the difference between these two, i am requesting u to clarify my doubt, or atleast refer some good book or reference paper where its equation has derived. thankyou,,