[kbaker]

I attempted to model cross flow of hot fluid (water) and cold fluid (air) into a finned 3D duct with fins like show in picture attached. The fins located at air side and there are three air inlets, three air interiors and three air outlets and the air flow in the axial direction while water enter from the top and exit from the bottom. I set the air inlet with temperature 300 K and water inlet at temperature 450 K and I used velocity inlet at both water and air when i run the case a reverse flow happen from all outlets and in spite i get convergence at last but temperature contours be equal to 300 at both fluids without any change? may somebody tell me what problem in my settings? knowing that
the duct length and height 16 mm and depth 8 mm??

regards
k.baker