Shuttlecock Simulation Issues

Topcat · February 2, 2024, 09:28

Good Afternoon,

I am attempting to simulate the flow over a shuttlecock but i am having issues with the geometry 'breaking' in the cfd-post section. I have attached an image.

Some info:
Currently the enclosure is defined as a fluid domain and the shuttle head and body as solid domain.

The top two components in the default domain (Default Domain Default and Default Fluid Solid Interface Side 1) seem to be the ones 'breaking' but in Domain 1 (the solid domain) they appear fine but do not give a drag reading.

Any advice on what to look at would be much appreciated.

Opaque · February 2, 2024, 09:59

Bizarre, but if all the faces exist, you should check by visualizing the 'Mesh Regions" to track down the source of the issue.

Domain 1 shows correctly, but it does not report the drag. There is no drag on a solid domain. The drag can only be reported/computed on the fluid side of the domain interface.

Topcat · February 2, 2024, 11:21

Thankyou for your response. I did not realise that the solid domain does not compute drag. Does this mean my shuttle should be in the fluid domain? As i am particularly interested in the drag of the shuttle.

Opaque · February 2, 2024, 12:19

Solids are needed only if you are computing something of interest WITHIN the solid; otherwise, it is represented by the boundary.

ghorrocks · February 2, 2024, 18:27

Opaque's point is a fundamental one - you do not need to model the solid, you put a cavity in the fluid domain and calculate the drag on that.

The patchy meshing in the tail section is because you used ICEM and did not set it up correctly, or you used the patch independant mesher (which uses ICEM) and did not set that up correctly either. I would recommend either using the patch dependant mesher or spending a bit of time with ICEM/patch independant mesher to learn how to use it.

Topcat · February 3, 2024, 10:37

Thankyou for your responses. I have defined the head as a boundary in the fluid domain. However, im unsure what to set the definition as, if i set the whole head to a wall i get an error for isolated fluid regions. However if i leave the bottom of the head not defined as a wall then the airflow goes into the head which should not happen as the head is not hollow and has a solid base. How can i define the head properly?

ghorrocks · February 4, 2024, 04:20

Have you done the CFX tutorials? You are wasting your time if you do not learn the basics. Example 8 would be very useful (Flow over a Blunt Body) as it is similar to yours.

Several of your problems are mesh related, and some are setup related. But do the basic CFX tutorials before you do anything else.

February 2, 2024, 09:59		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,804 Rep Power: 32	Bizarre, but if all the faces exist, you should check by visualizing the 'Mesh Regions" to track down the source of the issue. Domain 1 shows correctly, but it does not report the drag. There is no drag on a solid domain. The drag can only be reported/computed on the fluid side of the domain interface. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 2, 2024, 12:19		#4
Opaque Senior Member Join Date: Jun 2009 Posts: 1,804 Rep Power: 32	Solids are needed only if you are computing something of interest WITHIN the solid; otherwise, it is represented by the boundary. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 2, 2024, 18:27		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Opaque's point is a fundamental one - you do not need to model the solid, you put a cavity in the fluid domain and calculate the drag on that. The patchy meshing in the tail section is because you used ICEM and did not set it up correctly, or you used the patch independant mesher (which uses ICEM) and did not set that up correctly either. I would recommend either using the patch dependant mesher or spending a bit of time with ICEM/patch independant mesher to learn how to use it. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 4, 2024, 04:20		#7
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Have you done the CFX tutorials? You are wasting your time if you do not learn the basics. Example 8 would be very useful (Flow over a Blunt Body) as it is similar to yours. Several of your problems are mesh related, and some are setup related. But do the basic CFX tutorials before you do anything else. karachun likes this. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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February 2, 2024, 11:21		#3
Topcat New Member Join Date: Feb 2024 Posts: 3 Rep Power: 2	Thankyou for your response. I did not realise that the solid domain does not compute drag. Does this mean my shuttle should be in the fluid domain? As i am particularly interested in the drag of the shuttle.

February 3, 2024, 10:37		#6
Topcat New Member Join Date: Feb 2024 Posts: 3 Rep Power: 2	Thankyou for your responses. I have defined the head as a boundary in the fluid domain. However, im unsure what to set the definition as, if i set the whole head to a wall i get an error for isolated fluid regions. However if i leave the bottom of the head not defined as a wall then the airflow goes into the head which should not happen as the head is not hollow and has a solid base. How can i define the head properly?