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184.108.40.206 Solute Flux
The molar flux of solute relative to the solid matrix is given by the vector . Since solute viscosity is not explicitly modeled in a biphasic-solute material, the tangential component of on a boundary surface may not be prescribed. Only the normal component of the relative solute flux, , represents a natural boundary condition. To prescribe a value for on a surface, use:
<surface_load type="soluteflux" surface="surface1"> <flux lc="1">1.0</flux> <linear>0</linear> <solute_id>1</solute_id> </surface_load>
The optional parameter solute_id specifies to which solute this flux condition applies, referencing the corresponding list in the Globals section (Section 3.4.2↑). If solute_id is not defined, the default value is 1.
The flux element defines the flux magnitude. The optional parameter lc defines a loadcurve for the normal flux evolution. If omitted a constant flux is applied.
When linear is set to 0 (default) it means that the flux matches the prescribed value even if the surface on which it is applied changes in area as it deforms. Therefore, the net molar flow rate across the surface changes with changes in area. This type of boundary condition is useful if the solute molar flux is known in the current configuration.
When linear is set to non-zero it means that the prescribed flux produces a molar flow rate based on the undeformed surface area in the reference configuration. Therefore, the flux in the current configuration does not match the prescribed value. This type of boundary condition is useful if the net molar flow rate across the surface is known. For example: Let be the known molar flow rate (in units of moles per time [n/t]), let be the surface area in the reference configuration (a constant). Using “linear” means that the user prescribes / as the flux boundary condition (in units of moles per area per time [n/L t]). However, regardless of the type, the solute molar flux saved in the output file has a normal component equal to / , where area in current configuration.