Calculation of Heat Transfer in 3D Pipe
-----------------------------------------

In this tutorial heat transfer on a solid pipe will be studied. Case
with pipe cross section will be prepared, boundary conditions and
material properties will be defined on the mesh of the pipe with the
help of Elmer toolbox, that is included into Elmer module.  CAD file
of pipe will be imported into SMITER GUI and then appropriately
modified and meshed. Then the user will define material properties and
boundary conditions and assign them to the mesh. In the end the
computation will be run and results will be shown in the Paraview
module.

Examine model in the GEOQ and MESH module
``````````````````````````````````````````````````````````

Navigate to *~/smiter/study/elmer-pipe* and open study
elmer_pipe_example.hdf. In GEOQ and MESH module the user can find the
CAD model and mesh model with already defined groups for faces and volumes.
Groups are defined for boundary conditions

* **heatfluxBC:** Heat flux on the outer side of pipe

* **adiabaticBC:** For the purpose of this tutorial, we will specify
  zero heat flux on the cross section of the pip

* **htcBC:** surface on the inner side that is in contact with water

.. _elmer_case_GEOMPipe:
.. figure:: images/elmerPipeGEOM.png
   :align: center

   CAD model of pipe in GEOM module.

  
.. _elmer_case_MESHPipe:
.. figure:: images/elmerPipeSMESH.png

   Mesh of pipe in Mesh module.

Construction of CAD and mesh groups is the same as in EHF-pipe
tutorial.  Navigate to ELMER module as shown in figure
:numref:`elmer_pipe_case_activateELMERmodule`

.. _elmer_pipe_case_activateELMERmodule:
.. figure:: images/elmer_case_activateELMERmodule.png
  :align: center

  Select *ELMER* option to move to Elmer module.

Examine ELMER tree structure in Object Browser

.. _elmer_treeStructure:
.. figure:: images/elmerTreeStructure.png
   :align: center

   Elmer general case in Object Browser.

Right-click on *cylinder_heat_transfer* and click *Edit case*. The
dialog in figure :numref:`elmerEditCasePipe` appears on screen.

.. _elmerEditCasePipe:
.. figure:: images/elmerEditCasePipe.png
  :align: center

  Dialog for editing ELMER case.

Under *Select case type* tick option *3D.* Then click on
*Equations*. The dialog in figure :numref:`elmerHeatTransferPipe` is
shown on the screen. We can see that heat transfer equation is active.
  
.. _elmerHeatTransferPipe:
.. figure:: images/elmerHeatTransferPipe.png
  :align: center

  Dialog to select equation of the ELMER case.

In similar way one can examine defined boundary conditions by clicking
on *Boundary conditions* and material properties by clicking on
*Materials. With *Object properties* the user can assign boundary
conditions and materials to mesh groups, as discussed in EHF finger
tutorial. After finishing, click *Save case to ELMER
study*. Right-click on *cylinder_heat_transfer* and click *Compute
case*.

The result is stored in folder *elmer-compute*, that is stored in
*home* directory. Inside *elmer-compute* folder is a folder
*cylinder_heat_transfer* and inside is case0001.vtu, that contains
temperature distribution on the pipe. Navigate to Paraview folder and
load the file. Temperatures are shown in figure
:numref:`elmerHeatTransferPipe`.


.. _elmerTemperaturePipe:
.. figure:: images/elmerTemperaturePipe.png
  :align: center

  Temperatures on pipe.