calculation of mass flow rate from the inner part of a vertical cylinder in natural

manoj kumar dash · August 24, 2018, 07:56

Dear all

I am doing numerical simulation of fluid flow and heat transfer from a hollow vertical cylinder in fluent. I want to find out mass flow rate through the pipe. I am performing 2-D axisymmetric case. i draw a line in the cylinder domain, but i am getting mass flow rate in negative. Can anybody kindly suggest me how to calculate mass flow rate correctly and what is wrong in my approach.
Thanking you all in advance

subhankarnits · August 24, 2018, 08:02

R u calculating mass flow rate at outlet?

manoj kumar dash · August 24, 2018, 08:05

No as i am performing the problem in steady state the mass flow rate i expected to be same through out the inner portion of pipe as mean velocity will be same every where. I want to know why it is giving a negative value.

LuckyTran · August 24, 2018, 08:55

Negative means it's going the opposite direction as the normal vector when we're talking about surfaces. With lines, the outward normal vector follows the right hand rule.

Try drawing your line in the reverse and you should get a positive mass flow.

subhankarnits · August 24, 2018, 08:58

Quote:

Originally Posted by LuckyTran

Negative means it's going the opposite direction as the normal vector when we're talking about surfaces. With lines, the outward normal vector follows the right hand rule.

Try drawing your line in the reverse and you should get a positive mass flow.

Can you tell me in brief. I don't understand

manoj kumar dash · August 24, 2018, 10:57

Dear sire thank you very much. I have changed the y co-ordinate(reverse the position of two point), but i am getting the same negative value. Can you please tell me what you have done , had i done the same thing or am i not able to get what you told. Thanking you very much .

August 24, 2018, 07:56	calculation of mass flow rate from the inner part of a vertical cylinder in natural	#1
manoj kumar dash New Member manoj kumar dash Join Date: Feb 2016 Posts: 8 Rep Power: 10	Dear all I am doing numerical simulation of fluid flow and heat transfer from a hollow vertical cylinder in fluent. I want to find out mass flow rate through the pipe. I am performing 2-D axisymmetric case. i draw a line in the cylinder domain, but i am getting mass flow rate in negative. Can anybody kindly suggest me how to calculate mass flow rate correctly and what is wrong in my approach. Thanking you all in advance

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August 24, 2018, 08:02		#2
subhankarnits Member subhankar das Join Date: Jul 2018 Posts: 32 Rep Power: 7	R u calculating mass flow rate at outlet?

August 24, 2018, 08:05		#3
manoj kumar dash New Member manoj kumar dash Join Date: Feb 2016 Posts: 8 Rep Power: 10	No as i am performing the problem in steady state the mass flow rate i expected to be same through out the inner portion of pipe as mean velocity will be same every where. I want to know why it is giving a negative value.

August 24, 2018, 08:55		#4
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,672 Rep Power: 65	Negative means it's going the opposite direction as the normal vector when we're talking about surfaces. With lines, the outward normal vector follows the right hand rule. Try drawing your line in the reverse and you should get a positive mass flow.

August 24, 2018, 10:57		#6
manoj kumar dash New Member manoj kumar dash Join Date: Feb 2016 Posts: 8 Rep Power: 10	Dear sire thank you very much. I have changed the y co-ordinate(reverse the position of two point), but i am getting the same negative value. Can you please tell me what you have done , had i done the same thing or am i not able to get what you told. Thanking you very much .