Grid independence Study in Star CCM+

HHK · September 16, 2015, 05:25

Hi...

I am trying to simulate the forward motion of a ship in calm sea condition. The quantity I am interested is the free surface elevation at a particular point and I need to perform the grid independence test. I plotted RMS value of the free surface elevation at a point against number of cells, but it does not give me a proper graph..?..How do I do the test if my physical quantity of interest is free surface elevation..?

Any help will be appreciated...!!!...Thank you...

fluid23 · September 16, 2015, 08:52

If the figure of merit you are basing your mesh dependency study on is behaving randomly you either have a problem with your model or you need to choose a different figure of merit to focus on.

HHK · September 16, 2015, 10:35

Hi Matt...

Thank you very much for your reply and interest...Is there any other physical quantity I can check for my study...?

fluid23 · September 16, 2015, 12:00

That is a question you probably have to answer yourself. Think about what physical, quantifiable phenomena contribute to free surface elevation and then try to use those parameters. I am really not sure what to tell you beyond that, its sort of out of my field of expertise.

For models I typically analyze I would look at things like pressure drop, forces (pressure typically, but viscous if its important), velocities, etc...

HHK · September 16, 2015, 12:25

Hi Matt...

Thank you very much for your suggestions and time...Let me try some more variables...

September 16, 2015, 05:25	Grid independence Study in Star CCM+	#1
HHK Member HARIHARAN K Join Date: Oct 2014 Posts: 40 Rep Power: 11	Hi... I am trying to simulate the forward motion of a ship in calm sea condition. The quantity I am interested is the free surface elevation at a particular point and I need to perform the grid independence test. I plotted RMS value of the free surface elevation at a point against number of cells, but it does not give me a proper graph..?..How do I do the test if my physical quantity of interest is free surface elevation..? Any help will be appreciated...!!!...Thank you...

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September 16, 2015, 08:52		#2
fluid23 Senior Member Matt Join Date: Aug 2014 Posts: 947 Rep Power: 17	If the figure of merit you are basing your mesh dependency study on is behaving randomly you either have a problem with your model or you need to choose a different figure of merit to focus on.

September 16, 2015, 10:35		#3
HHK Member HARIHARAN K Join Date: Oct 2014 Posts: 40 Rep Power: 11	Hi Matt... Thank you very much for your reply and interest...Is there any other physical quantity I can check for my study...?

September 16, 2015, 12:00		#4
fluid23 Senior Member Matt Join Date: Aug 2014 Posts: 947 Rep Power: 17	That is a question you probably have to answer yourself. Think about what physical, quantifiable phenomena contribute to free surface elevation and then try to use those parameters. I am really not sure what to tell you beyond that, its sort of out of my field of expertise. For models I typically analyze I would look at things like pressure drop, forces (pressure typically, but viscous if its important), velocities, etc...

September 16, 2015, 12:25		#5
HHK Member HARIHARAN K Join Date: Oct 2014 Posts: 40 Rep Power: 11	Hi Matt... Thank you very much for your suggestions and time...Let me try some more variables...