# Material Model

All of the properties of materials to be used in the simulation are defined in this branch.

Every volume (fluid or solid) must reference a material model. The same material model may be shared by any number of volumes. Any material models that are not referenced are ignored. AcuConsole has three pre-defined commonly used material models, Air, Aluminium and Water.

You can also import most of the standard material models from a repository. Apart from these, you can define a completely new material by right-clicking Material Model > New.

You can then define the individual properties of each material model. In the material model definition, the first parameter is Material Type which allows you to choose if the material defined is a fluid or solid.

A material model must contain all of the necessary properties associated with the equations being solved in the problem. These equations are defined in the Auto Solution Strategy. A material model which has Material Type as fluid must include the following parameters:
Density
Any equation
Specific Heat
Temperature equations
Viscosity
Flow and turbulence equations
Conductivity
Temperature equations
Viscoelastic
Viscoelasticity equations
Diffusivity*
Species equations
Porosity
Flow with porous material
Diffusivity properties can be defined individually for each species when solving the species equations, as shown below.

In general, it is advised to always define the viscosity properties even if the flow equations are not being solved. Some material properties, such as the conductivity model with a constant Prandtl number, may require the viscosity defined.

Since only energy and mesh displacement equations are defined with Material Type-Solid, the corresponding material models need definition of only Density, Specific Heat and Conductivity.

A fully defined material model can be exported so that it can be used for future simulations. To export a material model, right-click on the model and select Export.