error in simlation of density dependent flow

Hello all,
I am trying to simulate a 3D density dependent model. Feflow stops the simulation and show the message:
"Nonpositive determinant for elemenent 104 ...."

How can I find that element in the mesh?
What can I do to fix my mesh???
Can I define the exact length of elements?

Dear chrisoula,

it is typical for density dependend problems that stability problems occur. To handle this, you have to refine the grid in all 3 directions. Additional a wise time-stepping is necessary. Furtheron you could try upwinding settings.
In my opinion, you should check this first, before you try to find and modify just one element.

Kind regards,
Wolfram

to find an element you can go to the mesh generator menu and browse the mesh with the enlarge button.

otherwise, export is to *.shp file and browse it with GIS program.

to define exact element type u can use the built-in option in the generator menu and decide number of elements. for example if you have a 1200m line and you wish a 40m element type 30 (i.e. 1200m divide to 30 elements give 40m to each element).

Elad :)