Its purpose is to define a boundary condition for a Partial Differential Equation (PDE).
The general syntax is
onbdy(ib1, ib2,...) id(u)+<expression>*dnu(u) = g onbdy(ib1, ib2,...) u = gwhere
ib
's are boundary identification numbers, <expression>
is a generic
expression and g a generic function.
The term id(u)
may be absent as in -dnu(u)=g
.
dnu(u)
represents the conormal of the PDE, i.e.
when the PDE operator is