[Techies]

Hi everyone,
I 'm trying to calculate Nusselt number on the cylinder surface in CFD post. But I got one problem, when i calculate Nu ave on the cylinder surface, i use
Tdiff=massFlowAve(Temperature)@outlet-massFlowAve(Temperature)@inlet
Tbulk=massFlowAve(Temperature)@inlet+(x+0.4846[m])*Tdiff/0.872[m]
h=Heat Flux/(Temperature-Tbulk)
Nu=h*0.0235[m]/0.0254[W m^-1 K-1]
Nuave=areaAve(Nu)@cylinder
with x is my cordination of cylinder, -0.4846 inlet, 0.872=(inlet->outlet)
0.0235: hydraulic diameter, 0.0254: thermal conductivity
My problem is the result from this which is negative, whereas my areaAve temperature on the cylinder is higher than Tbulk. My heat flux is positive, Temp out is higher than temp in.
Please, Anyone calculated the Nusselt on the cylinder(or Pin-fin) can help me understand and fix this problem.
Thanks .