# comparison of an implicit vs. explicit
one-dimensional finite differences program for solving the unsteady heat-flow-equation

The heat-flow
equation (without source-term):

The
input data-file (identical for both programs)

The explicit
version (Fortran 77 source code)

The implict
version (Fortran 77 source code)

A small programm
for comparison of the results (Fortran 77 source code)

New and nicer the same programs as scilab programs: explict, implicit (updated at 2012-03-07).

The programs calculate the heat distribution
at a 100m long row in one year, where the row has the following thermal properties:

- Heat conduction = 1.5
(W/(K m))
- Density * specific heat
= 1,380,000 (J/(m³ M))
- The time step is in both
cases 1 hour
- Initial temperature =
283.15 K
- Spatial step size 1 m
- At the first 3 grid nodes
there is a Dirichlet border condition with a T of 283.15 + 50 (K)

# The results:

## Explicit

## Implicit

## The difference

(really small - only at the borders
there is a bigger difference probably because of a malfunction of the SY-Subroutine):