Seyed, There is a vector called cell_cf for instance. It contains all integrated > material forces (summed up material forces from integration points) for > each cell. Each cell has 4 vertices and 8 DoFs in 2D. Hence, it has to be a > 8x1 vector. > [...] > Now imagine you have this vector which represents forces for each vertex, > e.g. vertex 1 has 0.010126 in X-direction and 0.007502 in Y-direction, > vertex 2 has 0.011509 in X-direction and -0.012249 in Y-direction and so > on... > So you have a FESystem<2>(FE_Q<2>(1),2) element, i.e. linear continuous elements with two components, and the vector represents corresponding local DoF values?
> How is one able now to take these vectors for each cell and assemble them > correspondent to the DoF and summarize the values for coinciding nodes. > Remember the values are computed within Gauss points and are just > summarized over integration points to one single vector for each cell. It > means there should be nothing stored on the nodes yet, but we have to take > the information to the global structure and node/vertices level. > For Q1 elements you have a nodal basis. In particular, assigning the value to the DoF with the corresponding support point and component is all you have to do. The Gauss quadrature points never include the vertices [1] so saying that the values represent forces for each vertex and at the same time that the values are computed within Gauss points sounds contradictory. You can find out about the (global) DoF corresponding to the (vertex_no)th vertex via cell->vertex_dof_index(vertex_no, i) where i loops through the number of components, i.e i=0 for the x-component and i=1 for the y-component. The position of the (vertex_no)th can be obtained by: cell->vertex(vertex_no) Note that this approach is only suitable for Q1 elements. For higher polynomial degree, you have to calculate the values for all the support points of the finite element. Best, Daniel [1] https://en.wikipedia.org/wiki/Gaussian_quadrature#Gauss.E2.80.93Legendre_quadrature -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
