Unit:
Κατεύθυνση Αστροφυσική, Αστρονομία και Μηχανική (ΒΑΣΙΚΗ ΦΥΣΙΚΗ)Library of the School of Science
Author:
Νικολαΐδης Μάριος-Ανδρέας
Supervisors info:
Πέτρος Ιωάννου Αναπλ. Καθηγητή (Επιβλέπων), Αποστολάτος Θεοχάρης Επίκ. Καθηγητής, Βλαχάκης Νεκτάριος Επίκ. Καθηγητής
Original Title:
Μελέτη της μετάβασης στην τυρβώδη κατάσταση σε εργαστηριακούς σωλήνες
Translated title:
Study of transition to turbulence in laboratory flows
Summary:
Using nonlinear optimization methods we calculate optimal initial disturbances
over base states in Waleffe's SSP model and Poiseuille 2D flow.For this method
both forward and adjoint equations are solved numerically and update the
initial condition on a conjugate gradient direction of the optimization
functional.Process is iterated until sufficient convergence is achieved.We
search for minimal perturbation energy for transition to the self-sustaining
regime and energy growth over target times for fixed initial energy.Comparison
of nonlinear optimals with linear in Poiseuille flow shows that structure of
optimals is mainly unchanged.
Keywords:
Nonlinear optimization, Hydrodynamic instability
