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• # Assignment 7: fvSolution

Posted by on February 4, 2024 at 8:02 pm

Hello Professor,

I have a question regarding the “nNonOrthoCorrectors” in the case of ‘MotorBike’. For the given assignment 7, under ‘fvSolution’ for SIMPLE sub-dict, the “nNonOrthoCorrectors” is set to 0 by default. As per the lecture, this should be set to at least 1, but in my case it is 0. Could you help me understand what 0 means in this case since the ‘MotorBike’ case has a complex geometry?

Regards,

Himanshu

• ### BarÄ±ÅŸ Bicer

Moderator
February 7, 2024 at 9:43 pm

Hi Himanshu,

In OpenFOAM, the “nonOrthogonalCorrectors” parameter is specified in the system/fvSolution file, which contains settings for the numerical solution algorithms. By adjusting this parameter, users can control the trade-off between solution accuracy and computational cost. Increasing the number of corrector loops can improve solution accuracy but also increases computational expense. Since this is only tutorial, and I dont need so much accuracy therefore it was set to zero which means that it wont make any additional iteration.

However, When the mesh is bad (non-orthogonality > 75-80), the pressure calculation can be corrected by running several additional iterations of the pressure equation (inner loop). This is schematically represented below:

as an example for the number of non-orthogonality acc. to my experience you can use as follows:

• if non-orthogonality < 70-75 : 0;
• if non-orthogonality > 75-80 : 1;
• if non-orthogonality > 80-90 : 2;
• if orthogonality > 90, becomes challenging to converge. so better to revise your mesh!

I hope it helps you.

Best