X-Y plot problem, please help

tobytoby · September 6, 2010, 02:13

Dear all,

I would like to plot a graph, or create a profile, which is velocity change against time step of a point.

My problem is, I cannot set the x-axis as "Time Step".

I realize that using "Execute Commands" could be a solution to save the velocity profile agaist time for a point. However, I am not familiar with this. Would there anybody be able to give some hints or helps ?

Thank you,
Toby.

bubuchacha · March 20, 2013, 05:20

Hi Toby, I am currently trying to plot a temperature against time steps. I face the same problem not able to set the x axis as time step. May I know have you solve the problem and how do you do it?

Look forward to hear from you.

flotus1 · March 20, 2013, 05:35

Am I right assuming you try to do this as a post-processing step?
Usually, it is not possible to do this because fluent does not store the data at every time step.

You should rather set up a monitor point before you start the simulation unless you can afford to write a data file for every time step.

bubuchacha · March 20, 2013, 05:42

I see. You are right, I am trying on Setup and CFD-Post. How can I set up monitoring a particular point [monitoring temp (y axis) vs time step (x axis)] ?

flotus1 · March 20, 2013, 05:51

First you need the monitor point: In Fluent, choose Surface -> Point

Now in the Monitors tab, create a new surface monitor. Choose the point you created and change the "get data every..." option to Time step.
The report type should be "vertex average"
You can also choose to write the data directly to a file or to plot it in fluent. If you do so, the option to set the x-axis to time step becomes available.

bubuchacha · March 20, 2013, 06:49

ok. ill give it a try.

do generating graph need tecplot ababus and so on? or ansys fluent itself is sufficient to plot?

flotus1 · March 20, 2013, 07:10

You can enable ploting the function in fluent.
It is your decision if this type of representation is sufficient.

Zheng · March 20, 2013, 07:49

Quote:

Originally Posted by tobytoby

Dear all,

I would like to plot a graph, or create a profile, which is velocity change against time step of a point.

My problem is, I cannot set the x-axis as "Time Step".

I realize that using "Execute Commands" could be a solution to save the velocity profile agaist time for a point. However, I am not familiar with this. Would there anybody be able to give some hints or helps ?

Thank you,
Toby.

using x/y plot u can't achieve this. however, u can monitor the velocity through Monitors/Surface Monitors. first u need to create a point that is the point ur interested.

bubuchacha · March 20, 2013, 21:57

Thank you very much Alex and Zheng.

I got the result. Another question, is it possible to write a jpeg of the graph in the allocated files? or should I manually print screen the graphs? I realise after configuring the surface monitor, i am able to get a temperature value of the particular point from the xy plot. what is the temperature at the xy plot? is the temperature an average or at a particular time step?

September 6, 2010, 02:13	X-Y plot problem, please help	#1
tobytoby New Member Toby Cheung Join Date: Aug 2010 Posts: 3 Rep Power: 16	Dear all, I would like to plot a graph, or create a profile, which is velocity change against time step of a point. My problem is, I cannot set the x-axis as "Time Step". I realize that using "Execute Commands" could be a solution to save the velocity profile agaist time for a point. However, I am not familiar with this. Would there anybody be able to give some hints or helps ? Thank you, Toby.

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March 20, 2013, 05:20		#2
bubuchacha New Member Elaine Wee Join Date: Oct 2012 Posts: 14 Rep Power: 14	Hi Toby, I am currently trying to plot a temperature against time steps. I face the same problem not able to set the x axis as time step. May I know have you solve the problem and how do you do it? Look forward to hear from you.

March 20, 2013, 05:35		#3
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,427 Rep Power: 49	Am I right assuming you try to do this as a post-processing step? Usually, it is not possible to do this because fluent does not store the data at every time step. You should rather set up a monitor point before you start the simulation unless you can afford to write a data file for every time step.

March 20, 2013, 05:42		#4
bubuchacha New Member Elaine Wee Join Date: Oct 2012 Posts: 14 Rep Power: 14	I see. You are right, I am trying on Setup and CFD-Post. How can I set up monitoring a particular point [monitoring temp (y axis) vs time step (x axis)] ?

March 20, 2013, 05:51		#5
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,427 Rep Power: 49	First you need the monitor point: In Fluent, choose Surface -> Point Now in the Monitors tab, create a new surface monitor. Choose the point you created and change the "get data every..." option to Time step. The report type should be "vertex average" You can also choose to write the data directly to a file or to plot it in fluent. If you do so, the option to set the x-axis to time step becomes available.

March 20, 2013, 06:49		#6
bubuchacha New Member Elaine Wee Join Date: Oct 2012 Posts: 14 Rep Power: 14	ok. ill give it a try. do generating graph need tecplot ababus and so on? or ansys fluent itself is sufficient to plot?

March 20, 2013, 07:10		#7
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,427 Rep Power: 49	You can enable ploting the function in fluent. It is your decision if this type of representation is sufficient.

March 20, 2013, 21:57		#9
bubuchacha New Member Elaine Wee Join Date: Oct 2012 Posts: 14 Rep Power: 14	Thank you very much Alex and Zheng. I got the result. Another question, is it possible to write a jpeg of the graph in the allocated files? or should I manually print screen the graphs? I realise after configuring the surface monitor, i am able to get a temperature value of the particular point from the xy plot. what is the temperature at the xy plot? is the temperature an average or at a particular time step?