I'm working on an Helical coil for an oil heater and I just started to calculate pressure drop and heat dissipation. Fluid (hot oil at 100F) is just entering from the bottom of the coil and is exiting at the top. I considered Heat conduction in solids and assigned Material to coil. After running the simulation I got that temperature doesn't drop for the first 12 loops, and then drastically decrease 30F in the last 3 loops. Of course this is not possible. What is wrong/missing? Any help is appreciate. Thanks.