% Local convection correlation for Graetz problem
function [Nux, NuL] = GrtzNux(Wall,fReD,NuInf,Z)
  LevNu=LevNuL(Wall,fReD,Z);                                     
  [NuL, OLev, n] = GrtzNuL(Wall,fReD,NuInf,Z);                   
  switch Wall
  case 'T'
    Nux=NuL-1/3*LevNu.^n./(NuL-OLev).^(n-1);                     
  case {'H','H1','H2'}
    Nux=NuL./(1+LevNu.^n./NuL/3./(NuL-OLev).^(n-1));             
  otherwise
    error('Wall= ''T'' or ''H''');
  end
end
