# G-DEMPack Tutorial 3: DEM Meshers

Previously, in some kind of manual, explain the fields in the mesher. Once that is explained, we can proceed to the meshers tutorial.

The tutorial that follows must include the GiD file containing the geometries and the assignation of groups. How that is done is explained in Tutorial 1. If any doubt, refer to the others tutorials.

### Point

In this simplest case, we only have to give the mesher a diameter for the sphere in point. To enter the mesher settings for the point, go to the DEM Element subtree, double-click on 'Use Advanced Meshing Features' and Choose Yes by using the inverted triangle that sits on the right of the default value of No. The fields corresponding to the different meshers will open after selecting Yes. The program now lets you choose which algorithm type you would like to use. In this case we must use the FEMtoDEM, the other one does not make any sense. About the criterion type, in this case it does not matter which one you choose because in this particular case the three methods coincide, so we just choose Node based. The mesher now asks you for a diameter and for the characteristics of the distribution. We can for example assign a diameter of size of 0.4m, a normal distribution and a standard deviation of 0.

### Line

When meshing the line group, we first have to choose the size of the FEM elements (line elements in this case), which will determine the distribution of spheres in space. We can do this by going to Mesh > Unstructured > Assign sizes on lines. In the window that shows up we can enter, for example, a value of 0.25 and click Assign. We then click on the line and press Esc. The previous window will show up again in case we would like to add more line entities. In this case is not necessary, so we just press Close to finish with this assignation. To enter the mesher settings for the line, we simply go again to the DEM Element subtree, double-click on 'Use Advanced Meshing Features' and Choose Yes. In this case we also choose the FEMtoDEM but choose the Element Centroid Base criterion instead. We enter a value of 0.15m, choose for example a Log distribution and a standard deviation of 0.15.