Source term bricks (and Neumann condition)

This brick adds a source term, i.e. a term which occurs only in the right hand side of the linear (tangent) system build by the model. If $f$ denotes the value of the source term, the weak form of such a term is

$${\int }_{\mathrm{\Omega }}fvdx$$

where $v$ is the test function. The value $f$ can be constant or described on a finite element method.

It can also represent a Neumann condition if it is applied on a boundary of the domain.

The function to add a source term to a model is:

add_source_term_brick(md, mim,
                      varname, dataexpr, region = -1,
                      directdataname = std::string());

where md``is the model object, ``mim is the integration method, varname is the variable of the model for which the source term is added, dataexpr has to be a regular expression of GWFL, the generic weak form language (except for the complex version where it has to be a declared data of the model). It has to be scalar or vector valued depending on the fact that the variable is scalar or vector valued itself. region is a mesh region on which the term is added. If the region corresponds to a boundary, the source term will represent a Neumann condition. directdataname is an optional additional data which will directly be added to the right hand side without assembly.

The brick has a working complex version.

A slightly different brick, especially dedicated to deal with a Neumann condition, is added by the following function:

add_normal_source_term_brick(md, mim,
                             varname, dataexpr, region);

The difference compared to the basic source term brick is that the data should be a vector field (a matrix field if the variable varname is itself vector valued) and a scalar product with the outward unit normal is performed on it.