[sidharath]

Hello all,

I am writing here to seek some information on exporting the transient results from CFX of every time step in an optimised manner.

I am solving an compressor acoustics grid using hybrid rans-les model in CFX with approximately 10 million cells.

For the purpose of mode decomposition, I need the pressure, temperature and velocity data of the complete grid for every time step.

I was wondering if there is any way in which i can export only the P, T and V data for each timestep in the form of csv or dat file?

The option of saving transient results leads in big .trn files (7-12 gig) and isn´t feasible to either save or manipulate the results files due to computational constraints. I know of the export results option in CFX but as per what i understand, that is only limited to surface data in cgns format, right?

I was wondering if there is any option like in star ccm+ to export results in the form of tables of desired variables? Any directions would be appreciated.

Thank you,
Sid

[ghorrocks]

Options which come to mind are:

1) Use CFD-Post and File/Export. This can be scripted, and will give you a text file (ie easy to read but slow and big file)
2) Use the export options in Solver Manager. There are more options than just CGNS.
3) CFX used to have couplings to MPCCI (http://www.mpcci.de/). That can give you super high speed access to variables as the simulation progresses as its purpose is to couple with other solvers. I do not know if this has been removed as CFX now couples nicely with other ANSYS solvers so the need for MPCCI is diminished. But if it still exists you will need MPCCI (which is commercial software) and I suspect the API to use it is not straight forward.

[sidharath]

Hi Glenn,
Thank you for the reply and like always, it is appreciated.

1. First solution works but the downside is I´ve to still save the .trn files and then open these .trn files to export the results into .csv via cfd post. Although, the solution works but i would prefer to find a way that gives the direct data instead of going through cfd post.

2. The export option in solver manager offers other formats than cgns. I didn´t know about the export option in the solver manager but only in the CFX-Pre, solver output configuration (that only gave the option to export the surface data).
I explored the export result option in the solver manager and it offers the cgns and other format but nothing that can be directly used by matlab (csv, txt, dat..). Although there was a 'custom user export' option and i was wondering if you´ve used that and you think it can be used to export in .csv format.

3. The MPCCI coupling tool is paid tool and honestly, that alone limit my reach to it.

In the ideal case, i would like to get some way to generate the results in .csv file like .trn right from the solver but till now, i don´t think i´ll be able to do that.
The second best option would either be using cfd post to export the results in .csv or solver manger to export in csv but the results would be in the range of 15,000 per running point and exporting manually wouldn´t be very productive.

This brings me to another question, i am acquainted with scripting in CFX/CFD-Post. I was wondering if you could point me towards some literature that can help me script this export operation in cfd post.

Thank you.

[ghorrocks]

1. Then write a session file script and automate it.

2. The custom user export requires you to write the export routine in C (I think). It does not export CSV, the export option from point 1 does that.

3. You get what you pay for

Learning session files in CFD-Post is easy. Record a session file, do some stuff, stop the session file and look at what it produces. Then you have an instant session file. If you want to do more complex stuff like perl script inside it then read the documentation on how this works.

[-Maxim-]

Hi,
you can export the complete data for every timestep via the command line command "cfx5mondata" for all you monitor points plus some additional CFX variables such as massFlow etc. Look it up in the manual and/or search this forum.

One part of my batch scripts looks like this:

@echo off
SET ansyspath=%ansyspath%;"C:\Program Files\ANSYS Inc\v180\CFX\bin\cfx5mondata.exe"
for %%* in (.) do set projectname=%%~nx*
set name=%name% %projectname%_001

%ansyspath% -res %name%.res -out %projectname%_tunnel_points.csv -nocoeffloops -varlist "TIME;CURRENT TIMESTEP;USER POINT,P_TUN_4P_1330;.........."

[sidharath]

Originally Posted by ghorrocks

1. Then write a session file script and automate it.

2. The custom user export requires you to write the export routine in C (I think). It does not export CSV, the export option from point 1 does that.

3. You get what you pay for

Learning session files in CFD-Post is easy. Record a session file, do some stuff, stop the session file and look at what it produces. Then you have an instant session file. If you want to do more complex stuff like perl script inside it then read the documentation on how this works.

Thank you Glenn.
I am taking the first approach. I´ve made the session script and crunching the time step (around 15,000 of them).
I am still looking for an efficient way.
I contacted MpCCI people too, their tools wasn´t of help (mapper and coupler).

[sidharath]

Originally Posted by -Maxim-

Hi,
you can export the complete data for every timestep via the command line command "cfx5mondata" for all you monitor points plus some additional CFX variables such as massFlow etc. Look it up in the manual and/or search this forum.

One part of my batch scripts looks like this:

@echo off
SET ansyspath=%ansyspath%;"C:\Program Files\ANSYS Inc\v180\CFX\bin\cfx5mondata.exe"
for %%* in (.) do set projectname=%%~nx*
set name=%name% %projectname%_001

%ansyspath% -res %name%.res -out %projectname%_tunnel_points.csv -nocoeffloops -varlist "TIME;CURRENT TIMESTEP;USER POINT,P_TUN_4P_1330;.........."

Thank you for the script Maxim.
I want to export the data for all the grid points at every time step but just monitor point. Any ideas on how to do that via command line.

[ghorrocks]

You can also access the solver manager export commands by command line. But you have already said they don't help you much, so this is not much help.

I would just write your CFD-Post session file and leave the computer crunching over the weekend. If you are going to do this more than once you should consider:
* Text files are a slow and inefficient way of transferring data and result in huge data files. You want to go binary files.
* CFX has a direct export functionality, but you need to write the C++ code to do it. This will be the most efficient way of getting large amounts out of CFX.