[EJH]

I have a "simple" simulation that's driving me nuts. I'm trying to prove the accuracy of the Petukhov-Gnielinski heat transfer coefficient correlation for thermal-entry length in a pipe (see http://www.cheresources.com/convection.shtml under section 1-3) using the following model: A 2.2m long pipe with inner diameter of 9.7mm. There's an unheated section 1.6m long (to achieve a fully-developed velocity profile), followed by a 0.6m long section with constant wall heat flux. Water is the fluid, and I'm using SST turbulence model. The Reynolds number is around 52000. The pipe wall temperature, mass-flow averaged mean temperature, and the resulting Nusselt number all have the correct shape, but the Nusselt number magnitude is off by a few thousand. I've tried all sorts of meshes. Any advice?