External_Flow_Cylinder_ND
Procedure External_Flow_Cylinder_ND(Re,Pr:Nusselt,C_d) returns the average Nusselt number and the drag coefficient for an isothermal cylinder in crossflow. The properties used to calculate the dimensionless numbers should be evaluated at the film temperature.
Inputs:
Re - Reynold's number [-], defined as
where
r is the density of the fluid
m is the viscosity of the fluid
D is the diameter of the cylinder
u_infinity is the velocity of the flow
Pr - Prandtl number [-], defined as
where
c_p is the specific heat capacity of the fluid
k is the conductivity
Outputs:
Nusselt - average Nusselt number assuming a constant wall temperature [-], defined as
where
h is the average heat transfer coefficient
C_d - coefficient of drag [-]
where
F_D is the drag force
A_fr is the frontal area
Notes
This procedure is called by External_Flow_Cylinder to calculate the Nusselt number and drag coefficient. The procedure uses the Churchill and Bernstein correlation(1977) as described in Nellis and Klein. It has been validated at all tested Reynolds numbers with Re*Pr>0.2. The coefficient of drag is based on the correlation presented in White (1991). Data for the coefficient of drag are available for Reynolds numbers up to 1E7.
The Reynolds and Prandtl numbers are based on fluid properties evaluated at the film temperature, which is the average of the free stream and the surface temperatures.
Example
call External_Flow_Cylinder_ND(Re,Pr :Nusselt, C_d)
Re=10000 [-]
Pr=0.8 [-]
{Solution: Nusselt=56.23 [-], C_d=1.095 [-]}