Hi. I have a problem with the modeling of conduction in CFX. I have one material with a different conductivity in-plane and through plane. How am I suppose to implement two different K's

maybe, you could create 2 domains with 1 K each one. I did not understand very much your geometry (domain).

You may resolve it by creating an expression for thermal conductivity change and click use expression while defining thermal conductivity for material.

I already try to create a expresion as a function of x, y, z. The problem is if you create a expresion of the form k1*x+k2*y+k3*z. CFX just added the different values of K together. In the solver output that can be seen as a value of K that correspond to k1+k2+k3. Making a expression is thus not a solution or CFX needs to have a function that a expresion can be made dependent of a direction in terms of e1,e2,e3

You cannot accomplish this with expressions alone. There is a beta feature which allows you to create an anisotropic material such as this. You should contact technical support for details.

-CycLone