What mass flow value?

gustavosimiema · November 2, 2015, 08:55

One additional question, I created the surfaces (holes of the pipe) in the Design Modeler as you suggested. Then Fluent recognized them as "interior". But in the CFD-Post I cannot find them to calculate the mass flow rate in each hole. Did I do something wrong?

RodriguezFatz · November 2, 2015, 09:34

Hmm... Can you select them in Fluent? You can use the "Reports->" functions to calculate mass flow.

RodriguezFatz · November 3, 2015, 02:33

Another idea: Is this compressible right now? Does it converge if you set it to incompressible?

gustavosimiema · November 3, 2015, 04:36

The mass flow worked thank you

Now it´s compressible (ideal gas)... I can try with incompressible to check weather converge or not... Thank you for the suggestion

gustavosimiema · November 4, 2015, 06:32

Hi...

As incompressible (constant density) I could not see difference. But I used the density from nitrogen calculated at 1Pa and 298K (~1.13e-5 kg/m3).

Or maybe should I use the density of nitrogen at standard conditions (1.14 kg/m3)?

RodriguezFatz · November 4, 2015, 07:13

Quote:

Originally Posted by gustavosimiema

As incompressible (constant density) I could not see difference.

What does that mean? Didn't it converge?

gustavosimiema · November 4, 2015, 07:21

Means that all parameters residuals were less then 1e-5 and continuity residual ~1e-2 as were for compressible one...

What do you think about the density calculation?

RodriguezFatz · November 4, 2015, 07:25

Density doesn't matter right now, just get convergence...
Did you try a second solver, such as "coupled"? I guess you use SIMPLE right now, correct?

gustavosimiema · November 4, 2015, 07:31

I tried SIMPLE and COUPLED...

I guess that my case is one of them that the continuity residual doesn´t achieve very low numbers because of a good initial guess... If I see the plot of some paramaters (Area weighted average) Velocity inlet, pressure inlet, velocity outlet... all of the converged to a constant and acceptable value...

gustavosimiema · November 4, 2015, 08:47

If you would run as incompressible... which density would you use? Calculated using 1Pa and 298K or using 101325Pa and 298K?

RodriguezFatz · November 4, 2015, 08:48

Some lower one, such as 1 Pa.

November 2, 2015, 09:34		#62
RodriguezFatz Senior Member Philipp Join Date: Jun 2011 Location: Germany Posts: 1,297 Rep Power: 26	Hmm... Can you select them in Fluent? You can use the "Reports->" functions to calculate mass flow. __________________ The skeleton ran out of shampoo in the shower.

November 3, 2015, 02:33		#63
RodriguezFatz Senior Member Philipp Join Date: Jun 2011 Location: Germany Posts: 1,297 Rep Power: 26	Another idea: Is this compressible right now? Does it converge if you set it to incompressible? __________________ The skeleton ran out of shampoo in the shower.

November 4, 2015, 07:25		#68
RodriguezFatz Senior Member Philipp Join Date: Jun 2011 Location: Germany Posts: 1,297 Rep Power: 26	Density doesn't matter right now, just get convergence... Did you try a second solver, such as "coupled"? I guess you use SIMPLE right now, correct? __________________ The skeleton ran out of shampoo in the shower.

November 4, 2015, 08:48		#71
RodriguezFatz Senior Member Philipp Join Date: Jun 2011 Location: Germany Posts: 1,297 Rep Power: 26	Some lower one, such as 1 Pa. __________________ The skeleton ran out of shampoo in the shower.

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November 2, 2015, 08:55		#61
gustavosimiema Senior Member Gustavo Join Date: Jun 2015 Posts: 121 Rep Power: 10	One additional question, I created the surfaces (holes of the pipe) in the Design Modeler as you suggested. Then Fluent recognized them as "interior". But in the CFD-Post I cannot find them to calculate the mass flow rate in each hole. Did I do something wrong?

November 3, 2015, 04:36		#64
gustavosimiema Senior Member Gustavo Join Date: Jun 2015 Posts: 121 Rep Power: 10	The mass flow worked thank you Now it´s compressible (ideal gas)... I can try with incompressible to check weather converge or not... Thank you for the suggestion

November 4, 2015, 06:32		#65
gustavosimiema Senior Member Gustavo Join Date: Jun 2015 Posts: 121 Rep Power: 10	Hi... As incompressible (constant density) I could not see difference. But I used the density from nitrogen calculated at 1Pa and 298K (~1.13e-5 kg/m3). Or maybe should I use the density of nitrogen at standard conditions (1.14 kg/m3)?

November 4, 2015, 07:21		#67
gustavosimiema Senior Member Gustavo Join Date: Jun 2015 Posts: 121 Rep Power: 10	Means that all parameters residuals were less then 1e-5 and continuity residual ~1e-2 as were for compressible one... What do you think about the density calculation?

November 4, 2015, 07:31		#69
gustavosimiema Senior Member Gustavo Join Date: Jun 2015 Posts: 121 Rep Power: 10	I tried SIMPLE and COUPLED... I guess that my case is one of them that the continuity residual doesn´t achieve very low numbers because of a good initial guess... If I see the plot of some paramaters (Area weighted average) Velocity inlet, pressure inlet, velocity outlet... all of the converged to a constant and acceptable value...

November 4, 2015, 08:47		#70
gustavosimiema Senior Member Gustavo Join Date: Jun 2015 Posts: 121 Rep Power: 10	If you would run as incompressible... which density would you use? Calculated using 1Pa and 298K or using 101325Pa and 298K?