Diffuse2d.

[dsumpter]

Hello everyone,

1. I am using a technique similar to Diffuse 2d for the diffusion of
heat and am slightly confused by one aspect. Consider a portion of
lattice with temperatures and first order diffusion:

   0
  080
   0 

If the diffusion constant is 1.0 and evaporation rate is 1.0 then the
centre value will update to 0 while the outside values will update to 
2. i.e.

   2
  202
   2

This appears somewhat unnatural for heat equations. If the value 8 came
from some source, you would not expect the source to be colder than
the surroundings on the next time step........

Am I right about this? Is there a theoretical explanation?

2. Has anyone got a reference they can give me discussing heat
diffusion in terms of lattices? I'd be very grateful.

Thanks,

David.