Flow around sphere using 2D axisymmetric

Thibalt · May 13, 2014, 12:27

Hi all,

I have a small question using 2D axisymmetry.
When simulating following problem in FLUENT, do I need to multiply the drag by factor 2 because I'm working with half a sphere? Or is the drag output from FLUENT already for a full sphere?
Image of the problem:

Thanks!

jafarizade · May 13, 2014, 12:47

hi
i am not sure but i think yes you should multiply it by two.

Thibalt · May 14, 2014, 04:39

Thanks for the answer, I would also think that I should double it. However, my results look more doubtful then.

jafarizade · May 15, 2014, 01:01

hi thibalt
did you check the reference values?
what did you put for the reference area?
it is important for making the drag doule or not.
best regards
ali

Thibalt · May 15, 2014, 05:33

Thank you jafarizade for your answer,

I use the drag force from FLUENT and not the drag coefficient calculated by the software using the reference values.
When I calculate Cd with the area of a full sphere, the solution matches experimental data. This seems weird since I did not double the drag data. So does this mean that the drag output is already for a full sphere?

jafarizade · May 15, 2014, 06:02

hi thibalt
i am not sure
but i think some thing else is wrong and you should make the drag double.
best regards
Ali

Thibalt · May 15, 2014, 06:05

Ok thanks! I will try to figure it out!

jafarizade · May 15, 2014, 06:08

good luck thibalt

May 13, 2014, 12:27	Flow around sphere using 2D axisymmetric	#1
Thibalt New Member Thibault Join Date: May 2014 Posts: 16 Rep Power: 12	Hi all, I have a small question using 2D axisymmetry. When simulating following problem in FLUENT, do I need to multiply the drag by factor 2 because I'm working with half a sphere? Or is the drag output from FLUENT already for a full sphere? Image of the problem: Thanks!

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May 13, 2014, 12:47		#2
jafarizade New Member Ali Jafarizade Join Date: May 2009 Posts: 22 Rep Power: 17	hi i am not sure but i think yes you should multiply it by two.

May 14, 2014, 04:39		#3
Thibalt New Member Thibault Join Date: May 2014 Posts: 16 Rep Power: 12	Thanks for the answer, I would also think that I should double it. However, my results look more doubtful then.

May 15, 2014, 01:01		#4
jafarizade New Member Ali Jafarizade Join Date: May 2009 Posts: 22 Rep Power: 17	hi thibalt did you check the reference values? what did you put for the reference area? it is important for making the drag doule or not. best regards ali

May 15, 2014, 05:33		#5
Thibalt New Member Thibault Join Date: May 2014 Posts: 16 Rep Power: 12	Thank you jafarizade for your answer, I use the drag force from FLUENT and not the drag coefficient calculated by the software using the reference values. When I calculate Cd with the area of a full sphere, the solution matches experimental data. This seems weird since I did not double the drag data. So does this mean that the drag output is already for a full sphere?

May 15, 2014, 06:02		#6
jafarizade New Member Ali Jafarizade Join Date: May 2009 Posts: 22 Rep Power: 17	hi thibalt i am not sure but i think some thing else is wrong and you should make the drag double. best regards Ali

May 15, 2014, 06:05		#7
Thibalt New Member Thibault Join Date: May 2014 Posts: 16 Rep Power: 12	Ok thanks! I will try to figure it out!

May 15, 2014, 06:08		#8
jafarizade New Member Ali Jafarizade Join Date: May 2009 Posts: 22 Rep Power: 17	good luck thibalt