typedef struct {
PetscReal normal[3]; /* Area-scaled normals */
PetscReal centroid[3]; /* Location of centroid (quadrature point) */
PetscScalar grad[2][3]; /* Face contribution to gradient in left and right cell */
} PetscFVFaceGeom;
Note: The components are
PetscReal normal[3] - Area-scaled normals
PetscReal centroid[3] - Location of centroid (quadrature point)
PetscScalar grad[2][3] - Face contribution to gradient in left and right cell