Assembly

The Assembly class holds most routines and objects related to assembling the numerical system, such as the ones listed below. In the non-exhaustive list below, we refer to as local the current element, face, quadrature points and neighbor values of each quantity.

• the current element

• the neighbor element

• the local volumes

• the Jacobian weights

• the local quadrature rules and points

• the local values of current variable, its spatial derivatives at first and second order, its curl on the element

It also contains these quantities for the mortar cases, on quadrature points.

This system is in charge of:

• reinitializing these quantities, through the reinit... methods, such as reinit(Elem* elem) for the current element, reinitAtPhysical(...) for a given vector of points or reinitFVFace(face_info) for the current face.

• getting the shape function values and its derivatives at the quadrature points, as well as the locations of the quadrature points from libmesh in the buildFE... routines for various locations.

• preparing the vectors for storing the local contributions to the Jacobian and the residual, by sizing and zeroing them, through the prepare... methods.

• caching contributions to the Jacobian and residual through the cache... methods. This can reduce the frequency of access to those global quantities, and is especially useful when using threads in the shared memory parallelism paradigm to be able to consider local contributions without locking the global vector.

• adding those local contributions to the global Jacobian and residual through the add... methods, for example addResidual for the local element residual or addJacobianNeighbor for the Jacobian on the neighbor element.