[Madhu Kalyan]

A 10 x 5 x 30 mm duct has been meshed with an element size of 0.5 mm. The flow cross-section of 50 mm2 has a flow rate of 0.005 kg/s (0.1 m/s) with water as the working fluid. The top and bottom walls have a heat rate of 3W on each of them and the inlet and outlet were made periodic in one case and kept as it is for another. The discretization was second order and the residuals were set to converge at 10-6. The periodic case has a small temperature dip at the beginning and sharp temperature rise at the end. . For reference purpose 300K is set as 0 and the results are displayed accordingly
plane location---Temperature periodic---Temperature non periodic
0___-0.00259___0.00484
2___ -0.06254___ 0.01959
4___ -0.04398___ 0.03922
6___ -0.02452___ 0.05871
8___ -0.00506___ 0.078
10___0.0144___ 0.09717
12___0.03386___ 0.11633
14___0.05331___ 0.13554
16___0.07277___ 0.15479
18___0.09223___ 0.17409
20___0.11169___ 0.19342
25___0.16033___ 0.24186
30___0.25352___ 0.28677


Can anybody tell me why this certain trend is happening? This seems to repeat for other cases too.