Different force for a symmetrical structure

rout86 · September 16, 2016, 11:36

I need to determine the force along x,y and z axis of a body where the fluid is water. I have considered a sphere and x-direction is the velocity inlet. The force measured along y and z axis are different. As the body is symmetrical then the force along y and z must be same. I don't understand why?

LuckyTran · September 21, 2016, 09:26

Are the differences small?

The body may be symmetrical but the solution is not guaranteed to be symmetrical because you are solving a discrete solution on a mesh that is probably not symmetrical. If you want to impose the additional constraint that these forces are the same, then you need to do so and declare this constraint explicitly.

If the differences are large, then you've probably made a mistake.

rout86 · September 21, 2016, 11:12

Thank you for the reply. Yes the difference is large. I am new to Fluent software so I am sure about the mistakes. But I am not able to recognize it. I am trying to determine the force along the x,y and z axis of an sphere.

September 16, 2016, 11:36	Different force for a symmetrical structure	#1
rout86 New Member Raja Rout Join Date: Sep 2016 Posts: 2 Rep Power: 0	I need to determine the force along x,y and z axis of a body where the fluid is water. I have considered a sphere and x-direction is the velocity inlet. The force measured along y and z axis are different. As the body is symmetrical then the force along y and z must be same. I don't understand why?

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September 21, 2016, 09:26		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,676 Rep Power: 66	Are the differences small? The body may be symmetrical but the solution is not guaranteed to be symmetrical because you are solving a discrete solution on a mesh that is probably not symmetrical. If you want to impose the additional constraint that these forces are the same, then you need to do so and declare this constraint explicitly. If the differences are large, then you've probably made a mistake.

September 21, 2016, 11:12		#3
rout86 New Member Raja Rout Join Date: Sep 2016 Posts: 2 Rep Power: 0	Thank you for the reply. Yes the difference is large. I am new to Fluent software so I am sure about the mistakes. But I am not able to recognize it. I am trying to determine the force along the x,y and z axis of an sphere.