A rectangular prism element (i.e., eight-node-linear element, rectangular parallelopiped element,  trilinear hexahedral element, or brick) shown below is a basic element for three-dimensional domains, used in TechFlowMP model. In a natural coordinate system (ξ,η,ζ), a shape function (basis function) for a rectangular prism element with eight nodes is written  as follows:

with Local node numbers:

The element has faces ξ = ±1, η = ±1 and ζ= ±1.

Local boundary face (plane) number: