Paras Kumar
Wolfgang Bangerth
>
> I have a query regarding writing the solution to a VTK file for visualization
> with PARAVIEW. If one wanted to do this via a mapping based on the
> displacement field, then one could simply follow the output_results() function
> of step-44.
> My question is that, Is it possible to write to the same vtk file, fields
> based on different MappingQEulerian
> data_out.build_patches
> function?
Paras:
No, you can't. But there is nothing that prevents you from creating two .vtu
files that contain different things, and visualizing the at the same time.
Both paraview and visit allow you to open several .vtu files at the same time
and showing their contents in the same window.
Best
W.
--
------------------------------------------------------------------------
Wolfgang Bangerth email: bang...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
Paras Kumar
Hi Wolfgang,
Thank you for the quick response.
I am fine with writing the displacement and the crack phase-field in separate files, as long as the objective of visualizing the phase-field on the deformed mesh is achieved.
Listed below are two possible ways of doing this (along with the issues/queries regarding them).
1. Write the phase-field in a separate file using a MappingQEulerian type object based on the displacement with nSubdivisions equaling the polynomial degree for FE ansatz of phase-field. The problem with this approach is that the command
dataOutDisp.add_data_vector(solution.block(0),
dispNames,
dealii::DataOut<dim>::type_dof_data,
dataCompIntepretationDisp);
dataOutDisp.build_patches(qMapping, polyDegrees[0]);
results in the following error:
An error occurred in line <1069> of file </calculate/iwtm99_lokal/Paras_HomeOffice/spack/var/spack/stage/dealii-9.0.1-jem5nejch2egpiislts7pg4o767wpuhu/dealii-9.0.1/include/deal.II/numerics/data_out_dof_data.templates.h> in function
void dealii::DataOut_DoFData<DoFHandlerType, patch_dim, patch_space_dim>::add_data_vector_internal(const DoFHandlerType*, const VectorType&, const std::vector<std::__cxx11::basic_string<char> >&, dealii::DataOut_DoFData<DoFHandlerType, patch_dim, patch_space_dim>::DataVectorType, const std::vector<dealii::DataComponentInterpretation::DataComponentInterpretation>&, bool) [with VectorType = dealii::Vector<double>; DoFHandlerType = dealii::DoFHandler<2, 2>; int patch_dim = 2; int patch_space_dim = 2]
The violated condition was:
data_vector.size() == dof_handler->n_dofs()
Additional information:
The vector has size 132372 but the DoFHandler object says that there are 198558 degrees of freedom and there are 65731 active cells. The size of your vector needs to be either equal to the number of degrees of freedom, or equal to the number of active cells.
A probable solution could be to create a new DOfHandler during each output call for both the displacement as well as the phase-field and attach the respective solution blocks to their DofHandlers. Not sure this would work since the mapping which would be used for the phase-field would be based on a different DoFHandler. Also, this would probably be computationally expensive (not sure?)
2. Another idea could be to write both of them in the same file as done in Step-44, but use nSubdividisions equaling either min or max of the polynomial degrees of the FE ansatz for the two variables. Since, I probably not yet fully understand the implication of the parameter nSubdivisions in the definition of build_patches() [https://www.dealii.org/9.0.0/doxygen/deal.II/classDataOut.html#a5eb51872b8736849bb7e8d2007fae086], could you please explain what happens in the below example.
Let pDisp=2 and pPF=3 (it is known that pPF >= pDisp always) be the polynomial degrees used for the FE ansatz of displacement and phase-field respectively.
a) What information would we loose for phase-field, if nSubDivisions=pDisp, since, there are 16 values available per cell, and we only visualize 9 in PARAVIEW? Are the non-vertex values used for interpolation of the phase-field on the 4 sub-cells or are they completely neglected?
b) If we use nSubDivisions=pPF, then we would have the best “possible” visualization for the phase-field, but how would the values of the displacement field be interpolated for the 27 sub-cells since in reality only values for 9 points per cell are known. Could this lead to incorrect visualization of displacement?
Best regards,
Paras
Wolfgang Bangerth
> dataOutDisp.add_data_vector(solution.block(0), [...]
> ...
> call for both the displacement as well as the phase-field and attach the
> respective solution blocks to their DofHandlers. Not sure this would work
> since the mapping which would be used for the phase-field would be based on a
> different DoFHandler. Also, this would probably be computationally expensive
> (not sure?)
visualize the fields that are in the other blocks, just don't visualize them
even though they are in the output file :-)
Cheers