  A method to bound the maximum energy perturbation for which regional
stability of transitional fluid flow models can be guaranteed is introduced.
The proposed method exploits the fact that the fluid model's nonlinearities are
both lossless and locally bounded and uses the axes lengths of the ellipsoids
for the trajectory set containment as variables in the stability conditions.
Compared to existing approaches, the proposed method leads to an average
increase in the maximum allowable energy perturbation of 29% for the
Waleffe-KimHamilton (WKH) shear flow model and of 38% for the 9-state reduced
model of Couette flow.
