I have a rectangle already draw and meshed with Gambit, and i need to set an initial temperature on the left side, i need to say that the up and de down edge are adyabatic. So how can I do this. Im new on Fluent.

Read your mesh into Fluent... Then, go to Define --> Boundary conditions and select the appropriate surface(s). Specify the surface to be a "wall" and within that specifications, select Thermal Condition = Heat Flux, and assign a value of zero as the heat flux. Zero Heat Flux = Adiabatic Wall.

ok, but i am working with 2d problem, and is there the possibility to set the edges as adiabatic? and how can I put a starting temperature of 300 degrees C on the left side of my rectangle?

Same reply as above... except run FLUENT 2D (double precision recommended) and set BCs on "line segments" representing the edge boundaries. (Also, can select edge and specify as wall boundary with wall temp = 300+273 K

follow the tuto 5 of fluent, same problem