Static Pressure

Rohini · March 25, 2010, 14:11

Hi everyone,

I am doing a blood flow simulation in fluent with velocity inlets and outflow boundary conditions. I expect the pressure drop from the inlets to the outlets to be no more than 6-8 mm Hg (800 Pa). When I run the simulation, the contours of static pressure show the minimum value as -2500 Pa ( at the outlets) and the max value to be the somewhere around 3200 Pa ( at the inlets), making the pressure drop 3200 + 2500 = 5700 Pa. I am not sure whats going on with the static pressure as the velocity contours look fine.
Did anyone face this problem? I would deeply appreciate any help.
Thanks,

Rohini

thecfduser · March 25, 2010, 16:07

Hi
how did u estimate ure pressure drop (the value of 800 Pa)?? from correlations???
correlations are done for fully developped flows:
1-as ure flow is not fully developped near the inlet, it is normal that u get large pressure drops in this region, especially because u are imposing a constant velocity profile ( the velocity passes quickly from the value V that u imposed to 0 on the wall)
2-to verify ure simulation, compare the correlation to the numerical pressure drop only in the region where the flow become fully developped

Finally, u must pay attention that blood is not a newtonian fluid. So choose carefully ire correlations.

Regards

March 25, 2010, 14:11	Static Pressure	#1
Rohini New Member rofluent Join Date: Feb 2010 Posts: 10 Rep Power: 16	Hi everyone, I am doing a blood flow simulation in fluent with velocity inlets and outflow boundary conditions. I expect the pressure drop from the inlets to the outlets to be no more than 6-8 mm Hg (800 Pa). When I run the simulation, the contours of static pressure show the minimum value as -2500 Pa ( at the outlets) and the max value to be the somewhere around 3200 Pa ( at the inlets), making the pressure drop 3200 + 2500 = 5700 Pa. I am not sure whats going on with the static pressure as the velocity contours look fine. Did anyone face this problem? I would deeply appreciate any help. Thanks, Rohini

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March 25, 2010, 16:07		#2
thecfduser Senior Member karine Join Date: Nov 2009 Posts: 158 Rep Power: 16	Hi how did u estimate ure pressure drop (the value of 800 Pa)?? from correlations??? correlations are done for fully developped flows: 1-as ure flow is not fully developped near the inlet, it is normal that u get large pressure drops in this region, especially because u are imposing a constant velocity profile ( the velocity passes quickly from the value V that u imposed to 0 on the wall) 2-to verify ure simulation, compare the correlation to the numerical pressure drop only in the region where the flow become fully developped Finally, u must pay attention that blood is not a newtonian fluid. So choose carefully ire correlations. Regards