Inlet Flowrate profile with time

Jotheman · October 17, 2015, 11:40

Hi Witches and Wizards of CFD

I need to create a csv file with about 720 points that inputs mass flow rate normal to 2D boundary surfaces. This data is unsteady flow rate captured at regular time intervals from a test rig and it needs to be used as the input boundary condition for a cfd domain in CFX. The data set looks like this

t0 m(dot)0
t1 m(dot)1
...
t720 m(dot)720

The data is very complex so we can’t use CEL to describe it accurately enough. I have seen many examples csv files that use the spatial (xyz) field but I only need the flow to be normal to the inlet face...and of course temporal fields and mass flow rate field in the input data file.

I hope the description isnt too vague. Any help will be appreciated.

Opaque · October 17, 2015, 12:01

From your description, it is not clear if you know the mass flow rate for each face of the mesh on the 2D surface, or the total mass flow rate through the 2D surface.

Jotheman · October 18, 2015, 10:13

Quote:

Originally Posted by Opaque

From your description, it is not clear if you know the mass flow rate for each face of the mesh on the 2D surface, or the total mass flow rate through the 2D surface.

I do! I have 720 points that form a mass flow rate curve over time. The data is the mass flow rate curve from an engine we're developing. I just need information on how I can use this data as inlet boundary conditions to a flow domain in CFX.

highorder_cfd · October 19, 2015, 12:51

The easiest approach is to interpolate your data in excel with a polynomial function (dx>add trend line on a plot) and implement your function MFR vs time in a single CEL function in CFX Pre.
Due to the Excel interpolation it is possible that points differ slightly from your experimental data, but overall in this way you have a single function to be implemented (in this way you will not have the problem to import all the tabular data in CFX.)

I hope this helps.

Opaque · October 19, 2015, 13:08

You can write a .csv file listing your experimental data

[Name]
My Mass Flow Rate

[Data]
Time [s], Mass Flow Rate [kg s^-1]

0.0 1.
0.01 1.001
...

...

Goto CFX-Pre->Tools->Initialize Profile Data.. Follow the wizard..

Now visit your inlet boundary condition, and use the profile you just imported..

I may have missed a detail or two, but that is the high level description of what you need to do..

October 17, 2015, 11:40	Inlet Flowrate profile with time	#1
Jotheman New Member Join Date: Oct 2015 Posts: 3 Rep Power: 11	Hi Witches and Wizards of CFD I need to create a csv file with about 720 points that inputs mass flow rate normal to 2D boundary surfaces. This data is unsteady flow rate captured at regular time intervals from a test rig and it needs to be used as the input boundary condition for a cfd domain in CFX. The data set looks like this t0 m(dot)0 t1 m(dot)1 ... t720 m(dot)720 The data is very complex so we can’t use CEL to describe it accurately enough. I have seen many examples csv files that use the spatial (xyz) field but I only need the flow to be normal to the inlet face...and of course temporal fields and mass flow rate field in the input data file. I hope the description isnt too vague. Any help will be appreciated.

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October 17, 2015, 12:01		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	From your description, it is not clear if you know the mass flow rate for each face of the mesh on the 2D surface, or the total mass flow rate through the 2D surface.

October 19, 2015, 12:51		#4
highorder_cfd Member Join Date: Jan 2015 Posts: 63 Rep Power: 11	The easiest approach is to interpolate your data in excel with a polynomial function (dx>add trend line on a plot) and implement your function MFR vs time in a single CEL function in CFX Pre. Due to the Excel interpolation it is possible that points differ slightly from your experimental data, but overall in this way you have a single function to be implemented (in this way you will not have the problem to import all the tabular data in CFX.) I hope this helps.

October 19, 2015, 13:08		#5
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	You can write a .csv file listing your experimental data [Name] My Mass Flow Rate [Data] Time [s], Mass Flow Rate [kg s^-1] 0.0 1. 0.01 1.001 ... ... Goto CFX-Pre->Tools->Initialize Profile Data.. Follow the wizard.. Now visit your inlet boundary condition, and use the profile you just imported.. I may have missed a detail or two, but that is the high level description of what you need to do..