Is OpenFoam Slower Than Starccm?

najunaju · March 17, 2013, 21:22

Dear All,

Greetings!

I am running, 2D simulation with standard kepsilon model, I have around 100k grid cells.

I run the 10 sec, simulation in Starccm V6. it takes around 4 days in single processor with all second order dicretization.

but the same simulation if I run in OpenFOAM by parallel computing (2 processors) to complete 10 sec simulation is takes 6.5 days. Single processor takes more.

My fvSchemes and fvSolution file are attached here. How can I speed up my case?

Please, help. I will be ever grateful.

fvSchemes.docx

fvSolution.docx

fsaltara · March 18, 2013, 11:58

In the fvSolution file, Try GAMG (multigrid method) to solve p and pFinal.

And I think that you should avoid under relaxation when using the PISO method. Under relaxation should be used when using the PIMPLE method and employing more than one outer corrector.

wyldckat · March 18, 2013, 17:39

Greetings to all!

Another possibility is the Operating System used. Since the initial attachments are of type "docx", that leads me to suspect that both Star-CCM+ and OpenFOAM were executed on Windows. It's best that you use both on Linux, for the best performance!

Yet another note: 2D in Star-CCM+ is probably optimized; while OpenFOAM always does things in 3D, although it can disable the 3rd dimension and run things as if it were 2D.

Best regards,
Bruno

najunaju · March 19, 2013, 03:40

Dear fsaltara and Bruno,

Greetings!

Thank you very much for your valuable suggestions. I run Starccm in windows and OpenFOAM in Ubuntu.

First, I run Kepsilon model without under relaxation than I found the simulation was used to explode after 10 to 15 iterations. Then I used UR to make the simulation stable. I will remove and try again as u guys have suggested.

Whatever, Thank you very much for our kind advice.

March 17, 2013, 21:22	Is OpenFoam Slower Than Starccm?	#1
najunaju New Member Md. Naimul Haque Join Date: Jan 2013 Posts: 14 Rep Power: 13	Dear All, Greetings! I am running, 2D simulation with standard kepsilon model, I have around 100k grid cells. I run the 10 sec, simulation in Starccm V6. it takes around 4 days in single processor with all second order dicretization. but the same simulation if I run in OpenFOAM by parallel computing (2 processors) to complete 10 sec simulation is takes 6.5 days. Single processor takes more. My fvSchemes and fvSolution file are attached here. How can I speed up my case? Please, help. I will be ever grateful. fvSchemes.docx fvSolution.docx

March 18, 2013, 11:58		#2
fsaltara New Member Join Date: Mar 2009 Posts: 21 Rep Power: 18	In the fvSolution file, Try GAMG (multigrid method) to solve p and pFinal. And I think that you should avoid under relaxation when using the PISO method. Under relaxation should be used when using the PIMPLE method and employing more than one outer corrector. wyldckat and najunaju like this.

March 18, 2013, 17:39		#3
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,975 Blog Entries: 45 Rep Power: 128	Greetings to all! Another possibility is the Operating System used. Since the initial attachments are of type "docx", that leads me to suspect that both Star-CCM+ and OpenFOAM were executed on Windows. It's best that you use both on Linux, for the best performance! Yet another note: 2D in Star-CCM+ is probably optimized; while OpenFOAM always does things in 3D, although it can disable the 3rd dimension and run things as if it were 2D. Best regards, Bruno __________________ OpenFOAM: FAQ \| Getting started Forum: How to get help, to post code/output and forum guide Read this before sending me PM

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March 19, 2013, 03:40		#4
najunaju New Member Md. Naimul Haque Join Date: Jan 2013 Posts: 14 Rep Power: 13	Dear fsaltara and Bruno, Greetings! Thank you very much for your valuable suggestions. I run Starccm in windows and OpenFOAM in Ubuntu. First, I run Kepsilon model without under relaxation than I found the simulation was used to explode after 10 to 15 iterations. Then I used UR to make the simulation stable. I will remove and try again as u guys have suggested. Whatever, Thank you very much for our kind advice.