Hi, I modified asf to include a species transport equation. I am using the same discretisation scheme and time stepping scheme as that of u(all,all,all,tc). I also introduced species mass fraction as u(all,all,all,mfuel).At inflow of a channel i give dirichlet BC to mfuel. But when species mass fraction gives oscillations when it reaches the outflow boundary. Why is this so? -- *Vinu Varghese *