Nice idea, pandura, tho it seems like the inner cylinder isn't the real problem. I figured it was a hollow thick-walled tube that could have dry ice inside it during the whole process but that was probably wishful thinking...
I like ko99's idea of clamping a heater around the screen.
Finder1 asked for a tool to design heat sinks. MacroFlow doesn't predict heat sink performance or component temperatures.
I haven't looked into MacroFlow in depth because it's pretty easy to quickly model simple systems on Flotherm CFD (whereas HeatsinkDesigner is faster and does some things...
I've used Flotherm before and clearly HeatSinkDesigner is not in the same class, but it's not really an either/or question. HeatSinkDesigner is just a well-designed, cheap, handy little tool. I tend to gravitate to it for quick feasibility checks. I haven't tried it yet for finding suppliers...
Roark's is unique, as far as I know, in it's wealth of plate and shell formulas. Bagman, your endorsement sounded only semi-enthusiastic, perhaps you know another source?