Constitutive Models

Constitutive models describe relations between various physical quantities. In a physics simulation they are used to model the response or state of material (solid, fluid, or a mixture) as a function of input variables. There are many types of constitutive models available in GEOS. These models are grouped together based on their input/output interface.

In an input XML file, constitutive models are listed in the <Constitutive> block. Each parameterized model has its own XML tag, and each must be assigned a unique name via the name attribute. Names are used to assign models to regions of the physical domain via the materialList attribute of the <CellElementRegion> node (see Element: ElementRegions). In some cases, physics solvers must also be assigned specific constitutive models to use (see Physics Solvers).

A typical <Constitutive> and <ElementRegions> block will look like:



    <!-- Define a compressible, single-phase fluid called "water"-->



    <!--Add water to the material list for region 1-->
       cellBlocks="{ hexahedra, wedges, tetrahedra, pyramids }"
       materialList="{ water }"/>


  ... remainder of problem definition here ...