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Sensitivity Derivatives for Non-smooth or Noisy Objective Functions in Fluid Design Problems
No full textQuasi-Conservative Lambda Formulation
No full textThe numerical simulation of inviscid transonic flows by means of a "modified lambda formulation" takes into
account the shock transition from supersonic to subsonic flow conditions, thus allowing the coupling of the
supersonic region with the shocked subsonic one and, as a consequence, the upstream movement of the shock.
The present methodology is applied to one- and two-dimensional transonic flows. Although the two-dimensional
flow calculations involve Cartesian coordinates and are limited to the thin-airfoil approximation, the method
can be generalized to arbitrary two- and three-dimensional flow cases. In all of the computed cases, the shock is
found to have appropriate strength and position for steady flow conditions and to move upstream properly when
a change in the downstream pressure warrants it
The Smoothed Sensitivity Equations Method for Fluid Design Problems
No full textWe consider shape optimization problems involving compressible fluid flows, which are characterized by
nonsmooth and/or noisy objective functions. Such functions are difficult to optimize using derivative-based techniques.
To overcome such a difficulty, we suggest an approach for estimating the sensitivity derivatives, based on a suitable
smoothing of the sensitivity equations, The smoothing affects only the sensitivity derivatives and not the accuracy of the
analysis. The basic mechanism by which the smoothing process achieves this result is illustrated with the help of an
inverse design problem involving an inviscid quasi-one-dimensional how having a closed-form solution. The convergence
properties and the computational efficiency of the approach are demonstrated on two inverse design problems involving
two-dimensional inviscid, compressible flows
The determination of heavy metals in the Ligurian Sea. II. The geographical and vertical distribution of Cd, Cu, and Ni.
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