[Dharma Vedula]

Obtaining wrong u-velocity profiles. Velocity at all y increases in x-direction. Results below for laminar flow through rectangular microchannel (H=0.1 mm, W=0.2 mm, L=50 mm, Re=100, Inlet velocity=0.449 m/s). Wrote SIMPLER algorithm in Python code. Followed Versteeg and Malalasekra. Is is due to any error in p or u boundary condition?

0.00000.00000.00000.00000.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000
0.01670.44900.40040.41420.42670.43830.44900.45890.46820.47690.48540.49370.50200.5031
0.03330.44900.63190.65510.67510.69360.71080.72660.74130.75530.76880.78200.79560.7974
0.05000.44900.71100.73760.76000.78060.79970.81730.83380.84940.86450.87930.89400.8960
0.06670.44900.63540.65860.67850.69690.71380.72950.74410.75800.77150.78460.79750.7993
0.08330.44900.40170.41560.42810.43970.45030.46010.46930.47800.48650.49480.50280.5039
0.10000.00000.00000.00000.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000

[lcarasik]

Without more information, it looks like you are applying your velocity profile boundary condition on your bottom wall (see the 0.1 in the line of 0.0).

[Dharma Vedula]

I am sorry. I forgot to remove the first column. It represents the distance in y-direction (vertical direction) from y=0 to y=0.1 (height of the rectangular channel). The second column onwards - the velocities at different distances from inlet in x-direction (flow direction).

But the pressure computed from this code is matching with standard value for laminar tube flow.

Pressure drop obtained from the present analysis = 21.85 kPa
Pressure drop calculated from Fanning's equation = 23.90 kPa

I wrote code for steady state SIMPLER algorithm.

I am giving below the profile after removing the first column. Sorry for the inconvenience, and thank you very much.
0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
0.4490 0.4004 0.4142 0.4267 0.4383 0.4490 0.4589 0.4682 0.4769 0.4854 0.4937 0.5020 0.5031
0.4490 0.6319 0.6551 0.6751 0.6936 0.7108 0.7266 0.7413 0.7553 0.7688 0.7820 0.7956 0.7974
0.4490 0.7110 0.7376 0.7600 0.7806 0.7997 0.8173 0.8338 0.8494 0.8645 0.8793 0.8940 0.8960
0.4490 0.6354 0.6586 0.6785 0.6969 0.7138 0.7295 0.7441 0.7580 0.7715 0.7846 0.7975 0.7993
0.4490 0.4017 0.4156 0.4281 0.4397 0.4503 0.4601 0.4693 0.4780 0.4865 0.4948 0.5028 0.5039
0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

[lcarasik]

Originally Posted by Dharma Vedula

I am sorry. I forgot to remove the first column. It represents the distance in y-direction (vertical direction) from y=0 to y=0.1 (height of the rectangular channel). The second column onwards - the velocities at different distances from inlet in x-direction (flow direction).

But the pressure computed from this code is matching with standard value for laminar tube flow.

Pressure drop obtained from the present analysis = 21.85 kPa
Pressure drop calculated from Fanning's equation = 23.90 kPa

I wrote code for steady state SIMPLER algorithm.

I am giving below the profile after removing the first column. Sorry for the inconvenience, and thank you very much.
0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
0.4490 0.4004 0.4142 0.4267 0.4383 0.4490 0.4589 0.4682 0.4769 0.4854 0.4937 0.5020 0.5031
0.4490 0.6319 0.6551 0.6751 0.6936 0.7108 0.7266 0.7413 0.7553 0.7688 0.7820 0.7956 0.7974
0.4490 0.7110 0.7376 0.7600 0.7806 0.7997 0.8173 0.8338 0.8494 0.8645 0.8793 0.8940 0.8960
0.4490 0.6354 0.6586 0.6785 0.6969 0.7138 0.7295 0.7441 0.7580 0.7715 0.7846 0.7975 0.7993
0.4490 0.4017 0.4156 0.4281 0.4397 0.4503 0.4601 0.4693 0.4780 0.4865 0.4948 0.5028 0.5039
0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

It looks as if there is an issue with your coefficients of your solver. Did you test it with a lid-driven cavity case? Elsewise, your solution should be symmetric along the centerline.