# How to define the inlet using an Interpolation Functions or Data sheet?

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 May 15, 2019, 11:01 How to define the inlet using an Interpolation Functions or Data sheet? #1 Member   Join Date: Feb 2019 Posts: 30 Rep Power: 7 Hello , I want to use the mass flow rate as the inlet, before I just defined it as constant value or write in the expression and use a function. However, the function what I used is just an approximate fuction calculated from my experiment date, that was not realistic. So now I just want to input the time point and the correspond mass flow rate, like create an Excel data and then use choose the ''Tool'' - ''Initialize Profile Date'' to upload the excel data (is that true, I don't have experience)? I will try that and want to know, what is the right form to write in the excel? Like: Time point [s] mass flow rate [kg s-1] 0 0 0.5 1.25 1 2.1 1.5 3.2 2 3.9 ... I tried, but it said ''Invalid format''. How could I input the data in a right way? Thank you!

 May 15, 2019, 16:23 #2 Senior Member   Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,167 Rep Power: 23 Just create a user function in cfx-pre. You can either type in the data points, or import a text file with just 2 columns of data (numbers only). Define the units of the independent variable time [s] and result variable [kg/s]. Then use this function as your inlet mass flow condition: MyFunctionName(t) 3nhu1 likes this.

May 16, 2019, 02:58
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https://www.sharcnet.ca/Software/Ans....html#i1310599

I attached an example with variable mass flow. Once imported into pre you can reference the profile by its expression as MassFlowRate.Mass Flow Rate(Time) within the boundary setup.
Attached Images
 profile.png (7.0 KB, 88 views)

May 17, 2019, 05:12
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Quote:
 Originally Posted by evcelica Just create a user function in cfx-pre. You can either type in the data points, or import a text file with just 2 columns of data (numbers only). Define the units of the independent variable time [s] and result variable [kg/s]. Then use this function as your inlet mass flow condition: MyFunctionName(t)

Thank you!

May 17, 2019, 05:20
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Quote:
 Originally Posted by AtoHM https://www.sharcnet.ca/Software/Ans....html#i1310599 I attached an example with variable mass flow. Once imported into pre you can reference the profile by its expression as MassFlowRate.Mass Flow Rate(Time) within the boundary setup.

Thank you!
I succeed in using txt to write the fuction. The pic is shown as flowing:
1111111.PNG
And then in the inlet using the user function, after loading it likes
MFR.Mass Flow Rate(), then the only thing needs to be done is add the Time like MFR.Mass Flow Rate(Time).

 May 17, 2019, 05:27 #6 Member   Join Date: Feb 2019 Posts: 30 Rep Power: 7 [solved and further question delete]

November 26, 2023, 18:00
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Quote:
 Originally Posted by IronLyon Thank you! I succeed in using txt to write the fuction. The pic is shown as flowing: Attachment 70000 And then in the inlet using the user function, after loading it likes MFR.Mass Flow Rate(), then the only thing needs to be done is add the Time like MFR.Mass Flow Rate(Time).
Many thanks- this helped me

 Tags data profile, initialize profile date, inlet, transient