Learning Forum

[Luca]

Hello to everyone, I am simulating a spiral microfluidic chip with a rectangular section. It's a pressure-based driven flow in which I impose as boundary condition a pressure inlet and a pressure outlet, for simulate the flow of water inside this channel, filled with air. I use a VOF method, for simulate the multiphase system. After 150 iteration several times i encountered this error: 

Error: arg(2nd) out of range in string-ref Error Object: 0

Someone could help me?? I am still blocked at this point since a week.

 

[raul.raghav]

So to be clear, the error shows up while you are running your simulation? And this error starts after ~150 iterations? And do you setup fluent to generate any backup files after certain number of iterations?

[Luca]

Thanks for your answer Rahul. Yes, I start the simulation and after 150 iterations this error appears. Few files that i save in these simulations are pressure surface integrals, velocity surface integrals, vof volume integrals and datas (every 150 iterations, cause it is a transient simulation and I would to do an animation with contour plots).

Luca

[raul.raghav]

Can you check if your write directory has any special characters like "%"? Check the file-name, folder-name and directory-name. If there are any special characters, modify it and try running your simulation.

[Luca]

Checked, no special characters. I attached image of cluster path. (with files in the directory)

[Luca]

Maybe, i have found the problem using your suggestion. Data file every 150 iterations were saved as "export-1". I'm trying to see if it was the problem.

Thanks for you help Rahul, I am new with CFD

[raul.raghav]

You're welcome Luca. Let us know if you were able to solve your problem. Good luck!

[Luca]

Updates: Same error at the same iteration. (I tried to change the pressure at the bc of the inlet, and also the time step, i changed also the name of the file data that i saved every 150 iterations). This nightmare is still appearing.

[raul.raghav]

Luca, the error is definitely related to the saving of the backup data file. Can you attach a screenshot of the "Automatic Export" window?

Additionally, refer the following Fluent help file and the attached screenshot if it helps you in any way:

Fluent Data types

[Luca]

[raul.raghav]

Can you try the simulation by exporting just the important variables in the "Quantities" column to see if that is causing the error? If that doesnt work, can you also try saving the file in a different folder? Good luck!

[Luca]

For sure is a problem regarding data files. I changed time steps in which i save datas to 100. Now this error appears at 100 iterations.

[Luca]

For the happiness of everyone is reading and mine, it's working. I don't know what was the real problem but was regarding "Automatic export". Following last Rahul suggestion, the simulation is stil going after 250 iterations!

Thanks!

Luca 

[raul.raghav]

I'm glad you were able to sort the issue Luca. Can you share a screenshot of the "Automatic Export" window so it might be useful for others facing the same or similar issues?

[Luca]

There is the screeshot of my "Automatic Export". Basically during my tests i changed rispectively: name of export, directory of saving and number of variables that will be saved. (and the number of time step when the data were saved, but this doesn't influence the problem). 

Now the simulation is still running, thanks to Rahul!