I have now discovered another error I think whic is concerning my mesh, altough the quality is not too bad (i think). My orthogonal quality is around 0,8 and skewness 0,19.

The error says: negativ k in xxx cells after linear solve. Negative epsilon in xx cells after linear solve. All neighbors negative on 13 cells.

I dont understand how to make my mesh acceptable, because iam no expert and i thought its good enough.

Thank you for your help.

Kind regards.