% Evaluates Rayleigh and Prandtl numbers and thermal conductivity 
function [RaL, Pr, kf] = Ra(Ts,Tinf,L,mat)
  g    = 9.80665;                                                  % gravity constant
  Tf   = (Ts+Tinf)/2;                                              
  [bf,nf,af,kf,Pr] = prop('expan','nu','alpha','k','Pr',mat,Tf);   
  RaL  = g*L.^3.*bf.*abs(Ts-Tinf)./nf./af;                         
end
