## One lecture on data assimilation using some actual data of the Corona disease as an example.

*The lecture introduces adjoint methods for fluid dynamics. The adjoint equations for the Navier-Stokes equations describe sensitivities of a certain quantity of interest (think of drag of an air-foil for example) to a certain input parameter (think of the profile of the air-foil). Classical sensitivity analysis would assume a profile and vary for example the chamber thickness to calculate the sensitivity. One change results in one sensitivity. Instead of changing the thickness and probing the drag the adjoint equations provide an equation to directly calculate the sensitivity for changing all surface points of the profile. The method is capable of calculating the sensitivities of millions of parameters in one step. This comes of course with an effort, but immediately pays off, when more than a handful parameters are to be investigated. In this lecture, the method is introduced and an application to a particularly simple example of an optimisation of an Epidemiology model for the COVID-19 pandemic presented, to illustrate the method. Then applications to several, more complicated, fluid dynamical problems are discussed.*

22/07/2020

The webinar can be reached at this Goggle Meet link:

meet.google.com/fyg-xgcy-uyh

at 11:30am (Italian time)

Joern Sesterhenn received his Ph.D 1995 at the ETH Zurich for a

dissertation on compressible Low Mach number flows. A after a

post doctorate at the University of Washington where he worked on

gravity currents, he was a researcher at TU Munich, working on

Hypersonic and channel flows. He was habilitated in 2004 and

became professor at the University of the Armed Forces in Munich

in 2006. From 2009 to 2019 he was Professor for Numerical Fluid

Dynamics at TU Berlin and is at the University of Bayreuth since

2020, where he hold the Chair for Mechanics and

Fluid-mechanics. His present research activities are compressible

jet flows. He studies areoacoustics and stability of starting

jets, explosive volcanic eruptions, impinging jets for cooling or

additive material technologies (coating) and sustainment of

turbulence in interstellar media by galactic jets. He uses

forward and adjoint direct Numerical simulation and started

experimental work recently.