Normal Flux
When specifying normal boundary fluxes as boundary conditions, it is assumed that the normal flux follows the deformed boundary.
The normal flux to the reference (undeformed) configuration is defined as
where the normal flux to the deformed configuration is defined as
Here, N is the normal to the undeformed boundary, n is the normal to the deformed boundary.
The normal fluxes in the material frame (undeformed configuration) and spatial frame (deformed configuration) are related to as
where the variable JA is the ratio between the deformed area and the reference area.
By default, you specify the normal flux γn to the deformed configuration (spatial frame), but it is also possible to specify the normal flux in the reference configuration (material frame), Γn. The frame in which the normal flux is given can be specify in the Advanced section.