How to preven reverse flow in pressure outlet

Khaled yousef · June 17, 2014, 16:22

hi All,
I am trying to model steam condensation and i have problems with reverse flow at pressure outlet. If i will set the volume fraction for secondary phase equal to 1 then the domain is filled with secondary phase. How we can prevent any phases to enter the domain and the outlet can be used only when no reverse flow to exhaust the flow.
Any help and suggestions will be nice.
Thanks

munjal · June 18, 2014, 07:45

hie khaled,
what is oultlet BC?. mainly it happens due to incorrect BC. try it by velocity outlet/pressure outlet/outflow etc.
hope this will help

Khaled yousef · June 18, 2014, 10:08

Thanks Munjal for your reply,
I tried all these Bcs but i still face the reverse flow. Due to condensation the pressure decrease and suck flow from the outlet boundary. I know that the only way is UDF to allow flow to go out only through boundary and in case of reverse flow it blocks the outlet and the outlet works as wall.
Thanks again

Boreas · June 21, 2014, 17:17

Hi Khaled,

I have about the same issue, did you find a solution for that?

http://www.cfd-online.com/Forums/flu...luid-flow.html

Khaled yousef · June 26, 2014, 12:41

Quote:

Originally Posted by Boreas

Hi Khaled,

I have about the same issue, did you find a solution for that?

http://www.cfd-online.com/Forums/flu...luid-flow.html

No, i still have the same problem with reverse flow at outlet due to condensation inside the domain. Please, let know if you have any solution for this issue

.

invadoria · June 26, 2014, 14:20

You can apply a nonreflecting boundary condition for velocity components at the outlet section to prevent reflections. Sommerfeld boundary condition is a good choice for nonreflecting boundary conditions. You can find some applications of Sommerfeld boundary condition in my blog:
http://cfd-civil.blogspot.com.tr/

jthiakz · June 29, 2014, 22:57

Is it new design or it is in test. Would like to know what's reality with that geometry. Also pls explain geom details.

June 17, 2014, 16:22	How to preven reverse flow in pressure outlet	#1
Khaled yousef New Member khaled yousef Join Date: Apr 2013 Posts: 8 Rep Power: 13	hi All, I am trying to model steam condensation and i have problems with reverse flow at pressure outlet. If i will set the volume fraction for secondary phase equal to 1 then the domain is filled with secondary phase. How we can prevent any phases to enter the domain and the outlet can be used only when no reverse flow to exhaust the flow. Any help and suggestions will be nice. Thanks

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June 18, 2014, 07:45		#2
munjal New Member munjal shah Join Date: Jun 2014 Posts: 2 Rep Power: 0	hie khaled, what is oultlet BC?. mainly it happens due to incorrect BC. try it by velocity outlet/pressure outlet/outflow etc. hope this will help

June 18, 2014, 10:08		#3
Khaled yousef New Member khaled yousef Join Date: Apr 2013 Posts: 8 Rep Power: 13	Thanks Munjal for your reply, I tried all these Bcs but i still face the reverse flow. Due to condensation the pressure decrease and suck flow from the outlet boundary. I know that the only way is UDF to allow flow to go out only through boundary and in case of reverse flow it blocks the outlet and the outlet works as wall. Thanks again

June 21, 2014, 17:17		#4
Boreas New Member Bora Join Date: Dec 2010 Posts: 8 Rep Power: 15	Hi Khaled, I have about the same issue, did you find a solution for that? http://www.cfd-online.com/Forums/flu...luid-flow.html

June 26, 2014, 14:20		#6
invadoria New Member Ender Demirel Join Date: Jun 2009 Location: Turkey Posts: 20 Rep Power: 16	You can apply a nonreflecting boundary condition for velocity components at the outlet section to prevent reflections. Sommerfeld boundary condition is a good choice for nonreflecting boundary conditions. You can find some applications of Sommerfeld boundary condition in my blog: http://cfd-civil.blogspot.com.tr/

June 29, 2014, 22:57		#7
jthiakz Member Thiagu Join Date: Oct 2012 Location: India Posts: 60 Rep Power: 13	Is it new design or it is in test. Would like to know what's reality with that geometry. Also pls explain geom details.