The \(\mathtt{T}\)-coercivity approach for mixed problems (Q6633600)

In this note, the T-coercivity approach is applied to general mixed problems, including unperturbed and perturbed saddle-point problems to derive a global inf-sup condition. The flexibility of the T-coercivity approach is demonstrated for classical linear mixed problems, including Stokes, electromagnetism, nearly-incompressible elasticity and neutron diffusion, both for the theoretical study of the problems and for their numerical approximation by finite elements. In most cases, this leads to explicit discrete operators, whereas the degree of explicitness depends on the problem that is studied.