I appreciate if someone advice me where to find a free multidimensional heat conduction fortran code.

there are few fea thermo/thermo-structural programs out there (you may not be able to separate the thermo from the structural-but hey you get structural analysis as well). you can try dr frank riegs z88 program which is interactive with pre/post processors and links to commercial cad/fea programs. it is fully 3-d and has lots of element types (some i've never heard of) he has linux,sgi and windows (at a price) versions see http://www.engr.usask.ca/~macphed/fi...s/node170.html for information also check out the "finite element method" section on the resources section of this page. also the internet finite element resources page http://www.engr.usask.ca/~macphed/fi...resources.html has links to freeware/shareware programs the're lotsa other places you can check such as asme mecheng list of shareware have fun