Element has Volume <=0

GiD Geometry
1

Once I press calculate and before any calculation is made, I receive the following error: Element 1808 has volume <=0, stop

But if I look in the model, I find the element that the element 1808 appears to have a surface. I don’t know about a volume, because it is a 2D model.

Part of the model was got by copying its left part (with the option “Mirror”). Might this be the reason why elements in the right part have negative volume?

Any ideas about how to solve this problem or what is its cause?

Thank you in advance!

2

Ok. I can answer myself. The problem when you use the mirror option to copy geometry is that the normal of the copied elements may be not coherent with the original elements. To solve this problem you can go to Utilities–>Swap normals and select the copied elements to swap their normal and thus make it coherent with the normals of the original elements.