How to use higher-order element
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By default, triangle elements will be used in the mesh and model. However, OpenFDEM also supports 
the quadratic triangle, quadrangle elements, quadratic quadrangle element and reduced quadrangle element, etc. 

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1 Code
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To run the model with quadrangle elements, users only need to add the following line after setting 
up the mesh size and before creating the mesh.

.. code-block::

    of.geometry.recombine 'rock' 



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2 Run the Program
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When the program runs, the mesh of the model will look like this.

.. figure:: ../../images/Gmsh/UCS_test_quad.png
    :alt: Uniaxial Compression Test Mesh with Quadrangle Elements
    :align: center

    Figure 1: Uniaxial Compression Test Mesh with Quadrangle Elements

The program will also show the mesh has quadrilateral elements.

.. figure:: ../../images/Command/UCS_Quad.PNG
    :alt: Uniaxial Compression Test Mesh with Quadrangle Elements
    :align: center

    Figure 2: Uniaxial Compression Test Mesh with Quadrangle Elements

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3 Full Script
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- `UCS_test_quad.of`_ (click to download from GitHub)

.. _UCS_test_quad.of: https://github.com/OpenFDEM-geomechanics/Examples/blob/main/CreateUniaxialCompressionTestwithQuadrangleElement/runme.of

.. literalinclude:: examples/CreateUniaxialCompressionTestwithQuadrangleElement/runme.of
    :lines: 37-110
    :emphasize-lines: 27-28

.. raw:: html

   <script src="//clustrmaps.com/globe.js?d=IJDdJTOZeBy5TaHUiVkIm7GLGSulnk0C2NzaC4-34QA">
   </script>