Finite element integration points and shape functions

Integration points and shape functions for different type of elements are predefined in the thermal solver and allow the discretization of a continuous domain and the approximation of its behavior using finite elements.

Integration points are located within each finite element, where the thermal solver performs numerical integration to evaluate the element's temperature. The accuracy of numerical integration directly affects the accuracy of the solution. The element's behavior is expressed in terms of mathematical functions, known as shape function, defined at these integration points. Shape functions, which are expressed as polynomial functions, are used to interpolate the values of the solution field at any point within the element based on known values at the element nodes. Shape functions satisfy properties, such as unity at their corresponding node and zero at other nodes, ensuring accurate interpolation within the element.

The examples show shape functions and graphical representation for supported 2D elements.

Element type Graphical representation Shape function
Linear triangle
Parabolic triangle
Linear quadrilateral
Parabolic quadrilateral
Linear tetrahedron
Parabolic tetrahedron