A fractional-order trace-dev-div inequality
Carsten Carstensen and Norbert Heuer
The trace-dev-div inequality in Hs controls the trace in
the norm of Hs by that of the deviatoric part plus the
Hs-1 norm of the divergence of a quadratic tensor field
different from the constant unit matrix.
This is well known for s=0 and established for orders
0≤ s≤ 1 and arbitrary space dimension in this note.
For mixed and least-squares finite element error analysis in linear elasticity,
this inequality allows to establish robustness with respect to the
Lamé parameter λ.