K-episilon model in FLUENT

Hua Gu

I want to set the boundary condition of inflow. The inflow is uniform, according to K-epsi model, k->0, and episilon->0. But if I set them as 0, I can not run k-episilon model, there will be error message. So I believe it should be small values for k and epsilon, but how small it should be. Can anybody help me? And if I want to set a far field boundary, which is free stream with constant pressure, can I use pressure inlet boundary or pressure outlet boundary condition, if I can, which is better? Thanks