Dear all,

I have just started studying Nektar++ for the purpose of adding a new type of element for my research. It is my pleasure to join this great user group.

As a first step, I'm exploring the function for reading my mesh in Swansea .plt format, which is virtual void Nektar::NekMesh::InputSwan::Process() within file library/NekMesh/Module/InputModules/InputSwan.cpp. Some improvements have been made to the function so it successfully converts a linear .plt mesh in Swansea format to a Nektar++ .xml session file with boundary faces on each surface fall into an individual COMPOSITE.
However, the function seems able to read the 3rd order tetrahedral mesh (at least for the connectivity), but the boundary faces are just linear triangles. Would the subsequent processing convert the linear faces into curved ones?
In fact, the NekMesh main function will crash after a successful return from InputSwan::Process():

[InputSwan]   Reading Swansea mesh file 'm6.plt'

[InputSwan]   # tetrahedra : 235377

[InputSwan]   # points     : 1079083

[InputSwan]   mesh order   : 3

[InputSwan]   ND           : 20

[InputSwan]   Mesh statistics:

[InputSwan]     - Mesh dimension       : 3

[InputSwan]     - Element dimension    : 3

[InputSwan]     - Has CAD attached     : no

[InputSwan]     - Node count           : 41093

[InputSwan]     - Edge count           : 281235

[InputSwan]     - Face count           : 475520

[InputSwan]     - Elements             : 235377

[InputSwan]     - Bnd elements         : 9532

[InputSwan]     - Number of composites : 19

[InputSwan]     - Lower mesh extent    : -125 0 -125

[InputSwan]     - Upper mesh extent    : 125 124.901 125

[InputSwan]   Element counts (regular/deformed/total):

[InputSwan]     - Triangle    : 0             9532          9532        

[InputSwan]     - Tetrahedron : 0             235377        235377      

[InputSwan]   Finished reading mesh.

[InputSwan]    - Element dimension        : 3

[InputSwan]    - Space dimension          : 3

[InputSwan]    - No. of nodes             : 41093

[InputSwan]    - No. of 3D elements       : 235377

[InputSwan]    - No. of boundary elements : 9532

[InputSwan]     - Elapsed time: 156.314s.

[OutputNekpp] Writing Nektar++ file 'm6.xml'

Fatal   : Level 0 assertion violation

Where   : /lustre/xi.zou/Documents/work_folder/nektar/nektar-v5.2.0/library/NekMesh/MeshElements/Face.cpp[79]

Message : Face nodes of tensor product only supported for quadrilaterals.

terminate called after throwing an instance of 'Nektar::ErrorUtil::NekError'

  what():  Level 0 assertion violation

Where   : /lustre/xi.zou/Documents/work_folder/nektar/nektar-v5.2.0/library/NekMesh/MeshElements/Face.cpp[79]

Message : Face nodes of tensor product only supported for quadrilaterals.

I look forward to hearing from the experts on NekMesh and a further discussion.

Best regards,
Xi

 

 

Dr. Xi Zou

xi.zou@swansea.ac.uk

 

Research Assistant

Zienkiewicz Institute for Modelling, Data and AI

Faculty of Science and Engineering

Swansea University

Swansea, UK