Introduction
============

For Code_Aster, an elementary calculation corresponds to a couple (type of finite element, calculation option). Examples of finite element types (type_element):


* MEDKTR3: DKTtriangulaire element with 3 knots


* THER_PENTA15: pentahedron thermal element with 15 knots

Examples of calculation options (option):


* RIGI_MECA: stiffness calculation (elastic behavior)


* FLUX_ELGA: heat flow calculation knowing the temperature at the nodes

In the rest of this document, the example that will serve as a guideline will be that of calculating the heat flow at the points of integration (FLUX_ELGA) of the elements PENTA15de the '3D' modeling of the phenomenon 'THERMIQUE' (type_element = THER_PENTA15).

We will assume that this elementary calculation does not yet exist but that option FLUX_ELGA already exists (for other finite elements) and that the type_element THER_PENTA15 also exists (he already knows how to calculate other options). In this material, we will try to answer the questions:


* What do you have to do to perform this new elementary calculation?


* What source files need to be modified or added?

Other questions relating to finite elements are dealt with in other documents:


* [:ref:`D5.02.03 <D5.02.03>`] How do I introduce a new elementary calculation option? (for example a new post-treatment)


* [:ref:`D5.02.04 <D5.02.04>`] How to introduce a new family of finite elements (modeling)?


* [:ref:`D5.02.01 <D5.02.01>`] How do I introduce a new quantity or new components into an existing quantity?


* [:ref:`D5.02.02 <D5.02.02>`] How do I introduce a new mesh type (mesh_type) or a new reference element (ELREFE)?

We already said in the summary that the introduction of a new elementary calculation in Code_Aster required 2 actions:


* the addition of a text block in the type_element catalog (here THER_PENTA15)


* the addition (or modification) of a Fortran routine called TE00IJ.F90

We will detail these two actions in succession.