CFX Reverse flow problem even if open boundary used

AdhavRohit · December 5, 2013, 06:33

I am Rohit

I am performing simulation of water flowing through centrifugal pump impeller (only impeller is considered) .
i am getting flow rate = zero and in report reverse flow is observed. i.e i am getting completely wrang results.
even if i use open boundary condition at outlet.
same problem appears for 38000 elements, 70000 elements and 1 lac elements of mesh. (structured mesh i created using turbogrid)

can anybody help me in this regard.?

siw · December 5, 2013, 07:35

What happens if you move your fluid domain boundaries further away from the impeller? See // Modeling Guide // 2. Boundary Condition Modeling // 2.3. Using Boundary Conditions // 2.3.3. Using Inlets, Outlets and Openings Figs 2.1 to 2.3 in the CFX v14.5 Help.

ghorrocks · December 5, 2013, 17:01

Have you checked you are at the right operating point? That means the flow rate and pressures are expected to work for the pump design and RPM. Also, are you sure the impeller is rotating in the correct direction?

December 5, 2013, 06:33	CFX Reverse flow problem even if open boundary used	#1
AdhavRohit New Member Rohit Adhav IIT Madras Join Date: Aug 2013 Posts: 10 Rep Power: 13	I am Rohit I am performing simulation of water flowing through centrifugal pump impeller (only impeller is considered) . i am getting flow rate = zero and in report reverse flow is observed. i.e i am getting completely wrang results. even if i use open boundary condition at outlet. same problem appears for 38000 elements, 70000 elements and 1 lac elements of mesh. (structured mesh i created using turbogrid) can anybody help me in this regard.?

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December 5, 2013, 07:35		#2
siw Senior Member Stuart Join Date: Jul 2009 Location: Portsmouth, England Posts: 742 Rep Power: 26	What happens if you move your fluid domain boundaries further away from the impeller? See // Modeling Guide // 2. Boundary Condition Modeling // 2.3. Using Boundary Conditions // 2.3.3. Using Inlets, Outlets and Openings Figs 2.1 to 2.3 in the CFX v14.5 Help.

December 5, 2013, 17:01		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Have you checked you are at the right operating point? That means the flow rate and pressures are expected to work for the pump design and RPM. Also, are you sure the impeller is rotating in the correct direction?