G-DEMPack manual

This manual explains how to run a DEM simulation with D-DEMPack on GiD.

Contents 1 Loading D-DEMPack 2 The GiD philosophy 3 The Kratos philosophy 4 The D-DEMPack philosophy 5 Model Definition Tree 5.1 DEM General Options 5.1.1 Bounding Box 5.1.2 Physical Options 5.1.3 Advanced Options 5.2 Solution Strategy 5.2.1 Parallel Type 5.2.2 Time parameters 5.3 Elements 5.4 Boundary conditions

Loading D-DEMPack

If you did not install GiD or D-DEMPack yet, follow the installation instructions here: D-DEMPack installation

Once you have finished the installation, open GiD and load the D-DEMPack Problemtype by clicking:

Data -> D-DEMPack

Note that a toolbar with 7 buttons has been added to the left side of the GiD working window. This toolbar is called "Model definition toolbar" and can be hidden and shown through the GiD utilities:

Utilities -> Tools -> Toolbars

The buttons in the Model definition toolbar do the following actions:

Button 1 - Link to the GiD Groups Management Window

Button 2 - Model Definition Menu

Button 3 - Materials Menu

Button 4 - Running Processes Management Window

Button 5 - Run this case

Button 6 - Show information about how this case is running

Button 7 - Stop this case

The GiD philosophy

GiD is a Pre and Post Processor, it is not an actual CAD tool. However, it can be used to draw geometries and mesh them. For complicated geometries, we recommend using a CAD tool and importing them into GiD for meshing (or import mesh and apply conditions directly). In case of drawing geometries with GiD, one must be aware that it uses a Hierarchical Structure: Volumes are created with a set of watertight Surfaces, Surfaces are created with a set of watertight Lines and Lines are created starting and ending in Points. If there are no Points, a Line cannot be created, and the same dependence holds for all levels. For more information about how to use GiD, visit GiD's home page or follow some tutorials

The Kratos philosophy

The way Kratos applies materials and conditions to the geometry or the mesh is using the Groups. A Group is a set of entities (either in Geometry or in Mesh). A Group can contain any Volume, Surface, Line, Point, Element or Node, no matter whether it is already belonging to other Groups.

The D-DEMPack philosophy

Since DEMPack is based in Kratos and programmed for GiD, it inherits the philosophy of both. The Groups will be the essential tool for assigning materials and conditions.

OPTION 1: Use the Groups Management Window to create Groups and move entities into the corresponding Groups. Go to the Model Definition Tree, fill in all the fields and assign conditions to existing Groups (the ones you just created).

OPTION 2: Fill in all the fields of the Model Definition Tree and when asked for any Group to assign the condition to, use the button for automatic creation of Groups (included in the mini window for condition assignation)

Model Definition Tree

The Model Definition Tree contains all the options that must be filled in order to run a DEM computation.

DEM General Options

Bounding Box

Bounding Box:

Bounding Box type:

Max X:

Max Y:

Max Z:

Min X:

Min Y:

Min Z:

Physical Options

Gravity value:

Gx:

Gy:

Gz:

Advanced Options

Clean initial indentations:

Virtual mass coefficient:

Rolling friction:

Solution Strategy

Parallel Type

Parallel type: locked to OpenMP (MPI will be available in the future)

Number of threads: set the number of threads you want to use for this computation. Do not choose more than the available threads on your computer or the computation will be slower.

Time parameters

Delta time:

Total time:

Screen info output:

Neighbour search frequency:

Elements

DEM element: double click on this item and a Mini Window will open. Choose an existing Material and assign it to an existing Group (or create the Group on-the-go)

Boundary conditions

Prescribed velocitites It allows the imposition of velocities to sets of DEM elements. Double click on this item and a Mini Window will open. It will impose initial velocities or fixed velocities for all time to the Groups of spheres you choose.

Inlet It allows the insertion of new DEM elements into the domain. Double click on this item and a Mini Window will open. Every Mesh Node will insert Elements. Mesh Nodes come usually from the meshing of Points, Lines, Surfaces(recommended) or Volumes. Assign this condition to a Group containing a Surface and the inner and boundary Nodes of this Surface will be generating new DEM elements with the parameters chosen.

DEM-FEM wall It marks a Surface as a Rigid Body which cannot be penetrated by the DEM elements. Double click on this item and a Mini Window will open. Choose the options and assign it to a Group containg Surfaces (avoid Groups containing Spheres)