ModelParts
are the essential data structure to hold FEM objects in Kratos.
Since the “physics” of a problem is provided by the Element
and Condition
which implement it, in order to describe a new physical problem one should provide a new ModelPart
describing the connectivity but also made of the relevant element technology.
In Kratos, essentially all of the FEM objects (Nodes
, Elements
, Conditions
, Properties
, ProcessInfo
) are managed by shared pointers, and can hence have multiple owners. This mean in the practice that a given, say, Node
may belong at the same time to multiple ModelParts.
A typical use case is that in which multiple physical problems should be solved on a single discretization of the problem. This is the case for example of the Fluid-Thermal problem that we will describe at the end of the tutorial. Kratos has a special Modeler
named ConnectivityPreserveModeler
that fills a modelpart by preserving the same connectivity as in the source model part while changing the element technology.
The resultant modelpart is a “free standing” root modelpart, completely independent of the original one. Nevertheless it shares:
- Pointers to the same nodes
- Same
ProcessInfo
- Same
Properties
- Same
Tables
as in the source modelpart.
The difference thus lays in the Element type being employed, which substitute in the new modelpart the element of the old modelpart with a new element implementing the desired physics.
The usage of the modeler is as follows:
modeler = KratosMultiphysics.ConnectivityPreserveModeler()
modeler.GenerateModelPart(self.main_model_part, self.thermal_model_part, "Element2D3N", "Condition2D2N")