Warning 88: Singular field on the surface of a triangle.

Altair Forum User

I see the following warning:

Warning 88: Singular field on the surface of a triangle.

What does it mean and what should I do to fix it?

JIF

This warning occurs when near fields are sampled on a triangle.  An accurate near field value can only be obtained when the sample point is a finite distance from the triangle. The sample distance from the triangle depends on the mesh size. A general guideline is that the near field should be sampled at least 1.5 times the triangle edge length from the triangle.

Altair Forum User

Hi Jif,

 

I got the same description under Warning 81.

 

Will that make the result inaccurate? or is it okay to ignore the warning?

 

If not,

Altair Forum User said:

A general guideline is that the near field should be sampled at least 1.5 times the triangle edge length from the triangle.

 

I didn't mesh my model myself. I let FEKO mesh it for me (my model is electrically large). How would I know what the smallest triangle edge length is?

 

Thanks,

Shashank

JIF

Hello shashank119,

 

Warning 88 has been removed since FEKO now detects these triangle singularities and changes the integration strategy to use a singularity cancellation routine. Thus, warning 88 is only applicable to older versions.

 

Regarding warning 81, the text description is 'Singular field on the axis of a segment' and thus it applies to segments, not triangles. I assume you are requesting the a near field value on the axis of a wire segment and there the field is singular. I would suggest that you move your near field request point away from the segment to avoid the warning. Again, I would not sample too close to the segment either (a distance equal to the length of the segment is safe, but I have not done an accuracy study in order to provide more details regarding the recommended sample distance).

Altair Forum User

Hello JIF,

 

Thanks for that. Yes you are right, I got the warning for a Segment.

 

My near field request is large, where the request points are spaced out uniformly at 1m. 

 

Any tips on how I can ensure the near field request is away from a segment? Is there a setting where I can just tell FEKO to not sample on a segment?

 

Thanks!

 

 

JIF

There is no easy way to just 'not sample on segment vertices', but the near field request has an option to 'sample on edges' or not and this moves the sample points by half a increment. Depending on your model, that could be the quickest way to avoid these points.

Altair Forum User

Hi JIF,

 

Thanks for that! will give that a go. This is incredibly useful. Appreciate your response.