Seminar

Ji?í Neustupa
 (Institute of Mathematics, Czech Academy of Sciences)

Spectral instability of a steady flow of an incompressible viscous fluid past a rotating obstacle

Abstract:

We show that a steady solution U to the system of equations of motion of an incompressible Newtonian fluid past a rotating body is unstable if an associated linear operator L has at least one eigenvalue in the right halfplane in C. Our theorem does not directly follow from a series of preceding results on instability, mainly because the associated nonlinear operator is not bounded in the same space in which the instability is studied. As an important auxiliary result, we also show that the uniform growth bound of the C_0 semigroup e^{Lt} is equal to the spectral bound of operator L.

Lucio Boccardo
 (Sapienza University of Rome)

Regularizing effect of the lower order terms in some nonlinear Dirichlet problems

Abstract:

See the attachment.
prof. RNDr. Eduard Feireisl, DrSc.
árka Nečasová, Milan Pokorný
chairmen