High pressure values at inlet and Loss of Mass flow at AMIs -- pimpleDymFoam

coolcrasher · April 14, 2016, 09:04

Hi All,

I have been running centrifugal pump steady and transient case in last few months. Steady case works fine with simpleFoam solver. But I have problem with transient case with pimpleDyMFoam.

There is a mass flow loss when fluid is flowing through AMI patches. Also pressure boundary condition is fixed value and zero at outlet, but at inlet the pressure occured is too high. It is almost 5 times more. Inlet boundary condition used is zerogradient.

We have calculated the torque values as well. The torque values agree quite well. But pressure values is the only problem.

I am sharing the case folder for further refence:
https://www.dropbox.com/s/kixdj7oomm...a_135.zip?dl=0

However the case folder cannot be run since I have removed files from polymesh folder. Since I cannot share the geometry details or mesh of the pump. However one have look at the setting I have used.

Please help me out in correcting the errors. Please guide where I have gone wrong

.

Also let me know in case you need any further information

coolcrasher · April 15, 2016, 05:41

Any help guys

tas38 · April 15, 2016, 12:26

A more appropriate boundary condition (well-posed) for the inflow patch would be totalPressure for p and pressureInletOutltletVelocity for U if you are not specifying the velocity at the inflow.

coolcrasher · April 18, 2016, 03:51

Hi Troy,

Thanks a lot for replying.

I have been using following boundary conditions.

For Vel:
Inlet -- fixed value of 5.5
Outlet -- zero gradient

For p:
Inlet -- zero gradient
Outlet -- fixed value of 0

Do u suggest me to use some fixed total pressure at inlet, instead of fixed inlet velocity ?

Please explain if I am not wrong

April 14, 2016, 09:04	High pressure values at inlet and Loss of Mass flow at AMIs -- pimpleDymFoam	#1
coolcrasher Member Sravan Kumar Join Date: May 2014 Posts: 57 Rep Power: 12	Hi All, I have been running centrifugal pump steady and transient case in last few months. Steady case works fine with simpleFoam solver. But I have problem with transient case with pimpleDyMFoam. There is a mass flow loss when fluid is flowing through AMI patches. Also pressure boundary condition is fixed value and zero at outlet, but at inlet the pressure occured is too high. It is almost 5 times more. Inlet boundary condition used is zerogradient. We have calculated the torque values as well. The torque values agree quite well. But pressure values is the only problem. I am sharing the case folder for further refence: https://www.dropbox.com/s/kixdj7oomm...a_135.zip?dl=0 However the case folder cannot be run since I have removed files from polymesh folder. Since I cannot share the geometry details or mesh of the pump. However one have look at the setting I have used. Please help me out in correcting the errors. Please guide where I have gone wrong . Also let me know in case you need any further information

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April 15, 2016, 05:41		#2
coolcrasher Member Sravan Kumar Join Date: May 2014 Posts: 57 Rep Power: 12	Any help guys

April 15, 2016, 12:26		#3
tas38 Senior Member Troy Snyder Join Date: Jul 2009 Location: Akron, OH Posts: 220 Rep Power: 19	A more appropriate boundary condition (well-posed) for the inflow patch would be totalPressure for p and pressureInletOutltletVelocity for U if you are not specifying the velocity at the inflow.

April 18, 2016, 03:51		#4
coolcrasher Member Sravan Kumar Join Date: May 2014 Posts: 57 Rep Power: 12	Hi Troy, Thanks a lot for replying. I have been using following boundary conditions. For Vel: Inlet -- fixed value of 5.5 Outlet -- zero gradient For p: Inlet -- zero gradient Outlet -- fixed value of 0 Do u suggest me to use some fixed total pressure at inlet, instead of fixed inlet velocity ? Please explain if I am not wrong