Source code for festim.exports.average_surface

import ufl
from dolfinx import fem
from scifem import assemble_scalar

from festim.exports.surface_quantity import SurfaceQuantity




class AverageSurface(SurfaceQuantity):
    """Computes the average value of a field on a given surface.

    Args:
        field (festim.Species): species for which the average surface is computed
        surface (festim.SurfaceSubdomain): surface subdomain
        filename (str, optional): name of the file to which the average surface is
            exported

    Attributes:
        see `festim.SurfaceQuantity`
    """

    @property
    def title(self):
        return f"Average {self.field.name} surface {self.surface.id}"



    def compute(
        self, u: fem.Function | ufl.indexed.Indexed, ds: ufl.Measure, entity_maps=None
    ):
        """Computes the average value of the field on the defined surface subdomain, and
        appends it to the data list.

        Args:
            u: field for which the average value is computed
            ds: surface measure of the model
            entity_maps: entity maps relating parent mesh and submesh
        """

        self.value = assemble_scalar(
            fem.form(u * ds(self.surface.id), entity_maps=entity_maps)
        ) / assemble_scalar(fem.form(1 * ds(self.surface.id), entity_maps=entity_maps))
        self.data.append(self.value)