Help Student with Indoor Wood Heating model
 

Hello folks,
I'm a student in a CFD class and I'm doing a project to model the heat distribution in a small cabin with a wood burning furnace. I am using Phoenics to make the model. I have a furnace (basically a heat source) and I've come to a crux at figuring how to model the walls.

My original plan is to have the interior of the home be the domain so i don't have to deal with the outdoor conditions, and the extra computational time. Then i though well i could set the inside wall temps as fixed and do a calc using 20F outdoor temp, estimated 60F inside temp and R-13 walls, which gives me a temp of 57 or so on the inside walls. But that just doesn't seem right to me.

Is there a better way to do this? Maybe put my building in a box just bigger than my building and give that space a fixed temp of 20F? But then how do i make the walls have the correct R-value, the material options in phoenics are limited.

Any help would be great.

Thanks,
-elake