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.. manual/packages/vertex-cfd/boundary_conditions.rst
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.. _sec_boundary_conditions:

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Boundary conditions block
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The boundary condition block is composed of successive sublists, each defining a specific boundary. Each boundary sublist must contain the following entries:

* `Sideset ID`: Name of the sideset. A list of sideset names may be provided if multiple sidesets share the same boundary condition.
* `Element Block ID`: Name of the element block.
* `Strategy`: Boundary strategy to be applied.
* `Data`: Sublist containing the boundary values for each physics.

The boundary strategy is physics-dependent and therefore specific to each physics module or package. Within the core packages provided by Vertex-CFD, the following boundary strategies are available:

* `IncompressibleBoundaryFlux`: incompressible Navier-Stokes equations, temperature equation, and induction-less MHD equation in a fluid domain.
* `ConductionBoundaryFlux`: temperature equation in a solid domain.
* `SolidInductionLessMHDBoundaryFlux`: induction-less MHD equation in a solid domain.
* `Multiphysics`: combines multiple boundary strategies on a given solid/fluid domain.

The `Multiphysics` strategy allows boundary conditions from different physics modules to be combined within a single boundary block.

.. note::

   In the current version of Vertex-CFD, the `Multiphysics` capability is only available for solid domains. Support for fluid domains is under development.
      
.. literalinclude:: ../xml-blocks/boundary_conditions.xml
   :language: xml
   :lines: 1-51
   :caption: `Boundary Conditions` block in XML input file for different physics modules when assuming a geometry with N mesh blocks and M sidesets.

The remaining of this section describes the content of the `Data` sublist, starting with `BOUNDARY DATA ...` in the above listing.

.. toctree::
   :maxdepth: 1
   :titlesonly:

   boundary_condition_conduction.rst