The Contributing Velocity node adds a velocity contribution uctrb to the velocity field ud that is computed from the flow model selected in the parent Porous Medium, Unsaturated Porous Medium, or Dual Porosity Medium feature. The total velocity field used in the continuity equation is therefore

Such velocity contributions can arise in multiphysics models that involve, for example, transport of solutes. If several Contributing Velocity nodes are added under the same parent feature, the contributions are treated additively. The sum of all contributing velocity fields is available in the variables name.Uctrb (material frame) and name.uctrb (spatial frame), with name being the Name of the physics interface (for example, dl).

Select a coordinate system from the Coordinate system list to specify the coordinate system in which the contributing velocity field is given. The default is the Global coordinate system. Note that the coordinate system used to specify the components of the contributing velocity field can be selected independently of the coordinate system of the parent feature.

The default contributing velocity field uctrb is User defined, which lets you enter the components of the contributing velocity field explicitly. If a matching velocity field is announced by another feature, it will be available in the selection list.

Select the Frame in which the contributing velocity field is specified. The default is the Reference configuration, which means that the velocity field follows the material under, for example, a rotation of the domain. If instead your contributing velocity field follows a fixed direction in space, select the Deformed configuration. This section is only displayed if Advanced Physics Options is activated and the spatial and material frame of the component differ, such as in the presence of a Moving Mesh or Solid Mechanics interface.