The Line Mass Source feature models mass flow originating from a tube region with infinitely small radius.
The Line Mass Source feature is available for all dimensions, but the applicable selection differs between the dimensions.
The source Mass flux,
![](images/comsol_ref_fluidflow.28.39.1.png)
, should be specified. A positive value results in mass being ejected from the line into the computational domain and a negative value means that mass is removed from the computational domain.