Handling boundary condition in Fluent

August 29, 2005, 22:22

Hi Fluent users, i have a question, like in the geometry the periodicity between the boundaries is a mixed type of translation and rotation.

the boundaries are periodic but in fluent while dealing with boundary conditions, i cant select the boundary as both translation and rotation.

any idea as how to handle the conditions if the periodicity is both translation and rotation.

thanks in advance

Alex Zak · March 24, 2013, 06:22

Quote:

Originally Posted by sak
;123800

Hi Fluent users, i have a question, like in the geometry the periodicity between the boundaries is a mixed type of translation and rotation.

the boundaries are periodic but in fluent while dealing with boundary conditions, i cant select the boundary as both translation and rotation.

any idea as how to handle the conditions if the periodicity is both translation and rotation.

thanks in advance

Hi Sak!

I am intresting this problem too) My mesh in this image
SWIRL_STABE.jpg
Do anyone have ideas how create both translation and rotation periodic in fluent?

Thanks
Alex.

vasava · March 25, 2013, 03:33

I think you could write a UDF about mesh motion that has both rotation and translation. This along with options about 'mesh motion' in 'Cell Zone Condition' should resolve your problem.

deepthishan · March 25, 2013, 05:27

hi
I am doing 3d modelling of a can combustor using k-e model.If I give mass flow inlet and pressure outlet or pressure inlet and pressure outlet I am getting total pressure at the outlet is more than total pressure at inlet.But there should be a pressure drop in reality in a combustor.Can u help

?

jthiakz · March 25, 2013, 08:01

Pls check the location / methods (massflow weighted\area weighted average).
# what is inlet mach number (assuming subsonic)
# what are teh values of To,Ptot inlet To,Ptot outlet values
# what is the Ps in and out

deepthishan · March 25, 2013, 10:35

Its subsonic and pin=200000 and pout=212000 and the case is running well and giving results but in reality there should be pressure loss and here pressure is increasing..lets consider cold flow T=300k.In both cold flow and hot flow total pressure is increasing..

Alex Zak · March 25, 2013, 15:21

Hi Vasava!
Thanks for you reply!

But I am some questions about this problem
Is it better to use: mesh motion or frame motion in my case?
And how I am can set velocity (translation and rotation) mooved mesh or referense frame? Constants?

August 29, 2005, 22:22	Handling boundary condition in Fluent	#1
sak Guest Posts: n/a	Hi Fluent users, i have a question, like in the geometry the periodicity between the boundaries is a mixed type of translation and rotation. the boundaries are periodic but in fluent while dealing with boundary conditions, i cant select the boundary as both translation and rotation. any idea as how to handle the conditions if the periodicity is both translation and rotation. thanks in advance

March 25, 2013, 05:27	Total pressure at the outlet is more than inlet	#4
deepthishan New Member deepthi Join Date: Feb 2013 Posts: 8 Rep Power: 14	hi I am doing 3d modelling of a can combustor using k-e model.If I give mass flow inlet and pressure outlet or pressure inlet and pressure outlet I am getting total pressure at the outlet is more than total pressure at inlet.But there should be a pressure drop in reality in a combustor.Can u help?

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March 25, 2013, 03:33		#3
vasava Senior Member Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 732 Rep Power: 23	I think you could write a UDF about mesh motion that has both rotation and translation. This along with options about 'mesh motion' in 'Cell Zone Condition' should resolve your problem.

March 25, 2013, 08:01		#5
jthiakz Member Thiagu Join Date: Oct 2012 Location: India Posts: 60 Rep Power: 14	Pls check the location / methods (massflow weighted\area weighted average). # what is inlet mach number (assuming subsonic) # what are teh values of To,Ptot inlet To,Ptot outlet values # what is the Ps in and out

March 25, 2013, 10:35		#6
deepthishan New Member deepthi Join Date: Feb 2013 Posts: 8 Rep Power: 14	Its subsonic and pin=200000 and pout=212000 and the case is running well and giving results but in reality there should be pressure loss and here pressure is increasing..lets consider cold flow T=300k.In both cold flow and hot flow total pressure is increasing..

March 25, 2013, 15:21		#7
Alex Zak New Member Alexey Zakharov Join Date: Feb 2012 Location: Moscow Posts: 8 Rep Power: 15	Hi Vasava! Thanks for you reply! But I am some questions about this problem Is it better to use: mesh motion or frame motion in my case? And how I am can set velocity (translation and rotation) mooved mesh or referense frame? Constants?