# FLUX_SENS#

FLUX_SENS = {flux_type} <bc_id> <blk_id> <species_id> {sens_type}
<sens_id> <sens_flt> <file_name>


## Description / Usage#

FLUX_SENS cards request the calculation of the sensitivity of an integrated flux with respect to a boundary condition or material parameter. As many FLUX_SENS cards as desired can be input to Goma. Definitions of the input parameters are as follows:

 {flux_type} A keyword that can have any one of the following values: FORCE_NORMAL FORCE_TANGENT1 FORCE_TANGENT2 FORCE_X FORCE_Y FORCE_Z VOLUME_FLUX SPECIES_FLUX HEAT_FLUX TORQUE AVERAGE_CONC SURF_DISSIP AREA VOL_REVOLUTION PORE_LIQ_FLUX CHARGED_SPECIES_FLUX CURRENT_FICKIAN CURRENT For every request, the specified sensitivity of the integrated diffusive flux followed by that of the convective portion over the requested boundary will be appended to the specified file. If the convective flux is not applicable (cf. FLUX card), the second quantity will be zero. In all cases the area of the face (covered by the entire side set) and the time value are also output. The boundary flag identifier, an integer associated with the boundary location (node set in EXODUS II) in the problem domain on which the integrated flux sensitivity is desired. An integer that designates the mesh block (material) from which the flux sensitivity integral should be performed. This has implications on internal boundaries. An integer that identifies the species number if an integrated species flux sensitivity is requested. {sens_type} A two-character entry that identifies the sensitivity type, where: BC denotes a sensitivity w.r.t. to a boundary condition parameter. MT denotes a sensitivity w.r.t. to a material property parameter. An integer that identifies the sensitivity. If BC is specified for {sens_type}, then this value is the BC card number. If MT is specified for {sens_type}, this value is the material number. A floating point number whose meaning is also dependent on the selection of {sens_type}. If BC is specified, this value is the BC data float number. If MT is specified, this value is the material property tag. A character string corresponding to a file name into which these fluxes should be printed.

## Examples#

Here is an example input deck:

Post Processing Flux Sensitivities =
FLUX_SENS = VOLUME_FLUX 1 1 0 BC 5 3 flux_sens.out
END OF FLUX_SENS


## Technical Discussion#

Currently, the flux sensitivities do not account for the implicit sensitivity of material properties. That is, $$dFORCE_X$$ / $$dBC_{float}$$ does not include a contribution from $$d\mu$$ / $$dBC_{float}$$ , but $$dFORCE_X$$ / $$dMT_{property}$$ should be done correctly. In addition, sensitivities of integrated fluxes in solid materials have not been implemented yet.

NOTE: In order to compute flux sensitivities with respect to Dirichlet boundary condition floats, the boundary conditions need to use the residual method in the input file as described in the Boundary Condition Specification introduction, i.e. the optional parameter should be set to 1.0.

No References.