Rob
Forum Moderator

OK, there are a few options. 

  • Heat source in a solid (meshed) tube
  • Heat flux/temperature/convection on the "other" side of the tube wall
  • Heat flux/temperature/convection on the wet side of the tube bounding the shell side fluid

All are valid, I'd probably go for convection on the wet wall, as that minimises the mesh requirements and probably good enough with some care.Â