Problems of plotting chart of massflow vs y in cfd post

yorkatmars · August 3, 2019, 03:22

Hi, everyone. I want to plot mass flow vs y of inlet but it still shows zero. Here's my method, plz name any mistakes I've made or any concern.

1. Create a 2D line,named it as "line one", and specified line type as cut.
2. Pick the data source at "line one".
3. Choose X Axis as "Y".
4. Choose Y Axis as "MassFlow".(This variable didn't appear as I click on the drop-down menu. I selected "MassFlow" in addition.)

But when I use function calculator it can calculate the right mass flow.
I've looked up all kind of threads or articles related to this kind of problem and tried it. But the chart still shows zero.
Thank you for reading my thread. Best regard.

MIDHUN@CFD · August 14, 2019, 12:35

why dont you plot velocity and convert it to mass flow

Светлана · August 14, 2019, 19:44

What is the location of that line?

yorkatmars · August 19, 2019, 05:37

the location is at the inlet.

yorkatmars · August 19, 2019, 05:38

How? Can I multiply velocity by density and area and plot it?

sufjanst · August 21, 2019, 04:11

I guess your problem is on how the mass flow is calculated in your function calculator. The mass flow is not a field variable, you need the surface area to calculate the mass flow. Usually this is done with a surface integration. And as your nodes, do not have an area, it is impossible to calculate a mass flow at the nodes.

You can try to calculate the mass flow per mesh-cell at the boundary.

m=rho*u*A, with A:area of the cell. But I don't know how to calculate the area of the cell. Maybe Fluent is capable on exporting the cell-area.

August 3, 2019, 03:22	Problems of plotting chart of massflow vs y in cfd post	#1
yorkatmars New Member Tzu Yu,Lin Join Date: Aug 2019 Posts: 3 Rep Power: 6	Hi, everyone. I want to plot mass flow vs y of inlet but it still shows zero. Here's my method, plz name any mistakes I've made or any concern. 1. Create a 2D line,named it as "line one", and specified line type as cut. 2. Pick the data source at "line one". 3. Choose X Axis as "Y". 4. Choose Y Axis as "MassFlow".(This variable didn't appear as I click on the drop-down menu. I selected "MassFlow" in addition.) But when I use function calculator it can calculate the right mass flow. I've looked up all kind of threads or articles related to this kind of problem and tried it. But the chart still shows zero. Thank you for reading my thread. Best regard. Last edited by yorkatmars; August 3, 2019 at 06:03.

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August 14, 2019, 12:35		#2
MIDHUN@CFD Member MIDHUN Join Date: Nov 2012 Location: calicut Posts: 45 Rep Power: 13	why dont you plot velocity and convert it to mass flow

August 14, 2019, 19:44		#3
Светлана Senior Member Svetlana Tkachenko Join Date: Oct 2013 Location: Australia, Sydney Posts: 407 Rep Power: 14	What is the location of that line?

August 19, 2019, 05:37		#4
yorkatmars New Member Tzu Yu,Lin Join Date: Aug 2019 Posts: 3 Rep Power: 6	the location is at the inlet.

August 19, 2019, 05:38		#5
yorkatmars New Member Tzu Yu,Lin Join Date: Aug 2019 Posts: 3 Rep Power: 6	How? Can I multiply velocity by density and area and plot it?

August 21, 2019, 04:11		#6
sufjanst Member Join Date: Mar 2016 Posts: 73 Rep Power: 10	I guess your problem is on how the mass flow is calculated in your function calculator. The mass flow is not a field variable, you need the surface area to calculate the mass flow. Usually this is done with a surface integration. And as your nodes, do not have an area, it is impossible to calculate a mass flow at the nodes. You can try to calculate the mass flow per mesh-cell at the boundary. m=rhouA, with A:area of the cell. But I don't know how to calculate the area of the cell. Maybe Fluent is capable on exporting the cell-area.