From the series
Institute of Thermomechanics Seminar
Aerodynamic Research on the Tip Sections of Long Rotor Turbine Blades
presented by Dr. Martin Luxa, IT AS CR, v. v. i.
4 February 2015, 10.00
Conference Room B
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Dynamic nonlinear elastic behaviour, non equilibrium dynamics, first observed as a curiosity In earth materials has now been observed in a great variety of solids. The primary manifestations of the behaviour are characteristic wave distortion, and slow dynamics, a recovery process to equilibrium that takes place linearly with the logarithm of time, over hours to days after a wave disturbance. »»»
Summary
Dynamic nonlinear elastic behavior, nonequilibrium dynamics, first observed as a curiosity in earth materials has now been observed in a great variety of solids. The primary manifestations of the behavior are characteristic wave distortion, and slow dynamics, a recovery process to equilibrium that takes place linearly with the logarithm of time, over hours to days after a wave disturbance. »»»
Full title: Optimization of coded excitations with Symmetry Analysis : Formalism and applications in NDT with perspectives in ultrasonic nonlinear imaging of bio-materials »»»
In the stability theory of shear layers, the term `local stability' refers to the stability properties of a particular velocity profile at a given position in the flow. When the basic flow develops the streamwise direction, e.g. in a growing boundary layer, the changing local stability properties can be mapped out downstream. If there are regions of local absolute instability then there is the possibility of a `global instability' of the entire flow. When the basic flow varies slowly in the downstream direction the global stability can be determined from the local stability. »»»
Large deformations of a solid are investigated. We use a polar decomposition of gradient matrix F = RW (R is rotation matrix, W is stretch matrix). Large deformations of solids involve local spacial interactions either in an extension or in a rotation. Because local interactions are well described by spacial gradient, matrix W intervene for extensions and matrix gradR intervene for rotations. Thus the free energy depends on W and on gradR. Moreover, free energy takes into account the local impenetrability condition. Reactions to this impenetrability condition are important in constitutive laws. »»»
Turbulence will be introduced as the typical state of real flowing viscous fluids (historical overview). Attributes of turbulence will be presented (diffusivity, deterministic chaos, fractal structure…). A mathematical model will be introduced and its basic properties will be shown including the Kolmogorov theory. Then a few phenomenological aspects will demonstrate the typical features of the phenomenon (stability, complexity…).
The aim of the Colloquium is to facilitate the exchange of up to date information and knowledge among specialists in dynamic of machines and mechanical systems. The main attention will be focused on: »»»
The aim of the conference is to discuss contemporary problems of fluid mechanics and to bring out latest results obtained in the course of solution of grant projects supported by grant agencies in Czech Republic and abroad. The attendance of experts from the academician institutes, technical universities and from the other research institutions is assumed. The official languages of the conference are English and Czech. »»»
Prague November 23-24, 2010 The 11th seminar will discuss the problems of interaction od dynamical systems with the surrounding liquid or gas environment and the problems of dynamic systems with feedback. »»»
The Institute of Thermomechanics AS CR, v.v.i., Prague, the Czech Society for Mechanics and the ERCOFTAC Czech Pilot Centre will organize Colloquium FLUID DYNAMICS 2010 held on October 20 – 22, 2010. »»»
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