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Old   February 15, 2022, 03:21
Default Calculate swirl number Converge
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velkon123
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Hello,
How can you calculate the swirl number in ConvergeCFD. I am not sure how to set up the "perform integration" menu. In addition, I was planning to use the following equations but I was doubting if vtan is understood as v_mag or as v_u or v_v when the axial direction is in the z-direction.
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Old   February 17, 2022, 09:59
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Kislaya Srivastava
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Greetings,

CONVERGE outputs dynamic.out which contains information on Swirl Ratio and Angular Momentum in each direction. dynamic_region*.out values are region-based. By default, the swirl axis is the Z axis. However, you can enable Case Setup > Output/Post-Processing > Output files > Dynamic output options and provide a rotation matrix to change your reference vectors. Using this option, you can also enable the output of Angular Momentum Flux across a region interface.

These results should help you obtain what you're looking for.

Hope this helps.

Sincerely,
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Old   February 26, 2022, 03:36
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Originally Posted by ksrivast View Post
Greetings,

CONVERGE outputs dynamic.out which contains information on Swirl Ratio and Angular Momentum in each direction. dynamic_region*.out values are region-based. By default, the swirl axis is the Z axis. However, you can enable Case Setup > Output/Post-Processing > Output files > Dynamic output options and provide a rotation matrix to change your reference vectors. Using this option, you can also enable the output of Angular Momentum Flux across a region interface.

These results should help you obtain what you're looking for.

Hope this helps.

Sincerely,
Dear Ksrivast,
Thank you for your response. I am still wondering however how to calculate the axial momentum for determining the swirl number. In addition, should you provide a rotation matrix in the dynamic output options which is in axial direction?
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Old   March 7, 2022, 04:46
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Dear Ksrivast,
Thank you for your response. I am still wondering however how to calculate the axial momentum for determining the swirl number. In addition, should you provide a rotation matrix in the dynamic output options which is in axial direction?
Hi does anybody know how to calculate the swirl number or the axial momentum using Converge?
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Old   March 7, 2022, 10:07
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Greetings,

Swirl is by default calculated wrt to the Z-axis in dynamic.out. If you want to calculate it along an axis inclined to the Cartesian axes, then you'll have to provide a dynamic rotation matrix through dynamic.in.

You can consider the following strategies to evaluate axial momentum over a volume:
1. From your 3D files and using a post processing tool, like Tecplot for CONVERGE, you can integrate density*(vel_axial_direction)*cell_volume over the entire volume.
2. You can consider adopting a UDF approach to calculate and output axial momentum as required.

To get a rough idea of axial momentum at a particular location, you can have a region interface (two different regions on either side) and use the regions_flow.out file to evaluate momentum across the region interface. The velocity in the regions_flow.out file is along the normal direction. So you can align your region interface accordingly.

Hope this helps. If not, please reach out to us at support@convergecfd.com. Please use your official email for all correspondence with Convergent Science. Please mention your request, attach your case setup and add the cfd-online thread, as reference.

Sincerely,
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