The following Churchill and Bernstein (1977) is applicable for an external cross flow over a cylinder. The formula is picked from the ASHRAE guide (2005) chapter 3 table 9 equation T9.13
Where :
function crossFlow_cylinder_ASHRAE extends Modelica.Icons.Function; input Modelica.SIunits.PrandtlNumber Pr; input Modelica.SIunits.ReynoldsNumber Re; output Modelica.SIunits.NusseltNumber Nu; end crossFlow_cylinder_ASHRAE;