PROGRAM

2nd WSEAS International Conference on

APPLIED AND THEORETICAL MECHANICS

 (MECHANICS '06)

Venice, Italy, November 20-22, 2006

The 5th WSEAS International Conference on APPLIED and THEORETICAL MECHANICS sponsored by WSEAS and WSEAS Transactions

Monday, November 20, 2006

PLENARY LECTURE 1

Fluid-Structure-Interaction: Fundamentals and Engineering Applications

Prof. Dr.-Ing. F.-K. Benra

University of Duisburg-Essen

Faculty of Engineering Sciences

Institute of Energy and Environmental Engineering

Chair for Turbomachinery

[email protected]

Abstract: Many processes in nature and technology can be described only by using laws and equations from different physical disciplines. Such examples, for which the arising sub-problems cannot be solved independently, are called multi-physics applications. A very important class of these multi-physics problems are the fluid-structureinteractions (FSI), which are characterized by the fact, that the flow around a body has a strong impact on the structure and/or on the movement of the body and the modification of the structure or the position of the body or a component of the body due to the flow has an influence on the flow which is not negligible. The two disciplines which are involved in this kind of multi-physics problems are the fluid dynamics and the structure dynamics which both can be described by the relations of continuum mechanics. Examples of FSI exist in many fields of the natural sciences and the technology. Solutions for the mathematical description of fluid structure interactions can be obtained only by numerical simulations, which still today are a big challenge of scientific computation. In this contribution initially the fundamental relations for the calculation of the flow behavior and of the structure dynamics will be presented and approaches for numerical solutions of coupled FSI-systems will be pointed out. Afterwards different kinds of coupling methods for the two disciplines and possible methods of partitioning of the numerical simulations are described in detail and evaluated regarding the dependence of the two disciplines from each other. A detailed discussion of solutions for several FSI-examples brings the contribution to conclusion.

PLENARY LECTURE 2

The principle of Turbulent Frame Indifference in Large Eddy Simulation

Professor Francesco Gallerano

Dipartimento di Idraulica

Facolta di Ingegneria

Universita di Roma "La Sapienza"

ITALY

[email protected]

Abstract: In the framework of ordinary continuum thermodynamics turbulence models could be interpreted as constitutive equations which are necessary to close the equations of motion and the internal energy equation. The principle of Turbulent Frame Indifference is the equivalent in turbulence of the principle of Material Frame Indifference and implies form-invariance and frame indifference on the turbulent closure relations (Hutter & Joenk, 2004). Sadiki and Hutter (1996) emphasized that form-invariance and frame-independence are two distinct matters. A turbulent closure relation is form-invariant if it does not modify its formal expression under transformations of the frame and is constructed only with objective tensors. A turbulent closure relation is frame indifferent if it is expressed in terms of tensors that are independent of the angular and translational velocity of the frame. Weiss and Hutter (2003) emphasized the difference between the form-invariance and the frame indifference by underlining the existence of tensors that are objective but dependent on the angular velocity of the frame. A turbulent closure relation, which is expressed in terms of objective tensors that are dependent on the angular velocity of the frame, does not fulfil the principle of Turbulent Frame Indifference, because it is form invariant but frame dependent. Must all the turbulent closure relations fulfil the Principle of Turbulent Frame Indifference? The turbulent phenomena are not associated to the properties of the materials: consequently, turbulent closure relations do not represent the material behaviour. Turbulent closure relations must always be form invariant, but must not necessarily be frame indifferent (Hutter & Joenk, 2004). In other words not all the turbulent closure relations must fulfil the principle of Turbulent Frame Indifference. In the turbulent closure relations, the modelled expressions of an unknown objective tensor must be formulated in terms of objective tensors (allowing the closure relations to fulfil the requirement of form invariance) and must retain the same dependence (on the angular velocity of the frame) of the unknown tensor. As demonstrated by Gallerano et al. (2005), the generalised SGS turbulent stress tensor in LES is an objective tensor and is independent of the angular and translational velocity of the frame. Consequently, the closure relation for this tensor must fulfil the principle of Turbulent Frame Indifference. A new closure relation for the generalized SGS turbulent stress tensor is presented. In the proposed model the generalized SGS turbulent stress tensor is related to the generalized SGS turbulent kinetic energy and its viscous dissipation. It is demonstrated that the balance equation of the viscous dissipation is form-invariant but frame-dependent under Euclidean transformations of the frame; the proposed closure relations allow the modeled balance equation of the viscous dissipation to respect the properties of form-invariance and frame-dependence of the exact equation.

PLENARY LECTURE 3

Geometric Moire and its Applicability for Dynamical Systems

Professor Minvydas Ragulskis

Department of Mathematical Research in Systems

Kaunas University of Technology

Studentu 50-222, Kaunas LT-51638, Lithuania

[email protected]

Abstract: Geometric moire is classical full-field non-destructive optical experimental technique applied for measurement of in-plane fields of deformation and strain. It is based on subtractive superposition of moire gratings which are usually comprised from arrays of parallel lines. Patterns of moire fringes are produced when image of the grating in the state of equilibrium is superposed with another image of the deformed grating.

What would happen if moire grating would oscillate and time averaging techniques would be used to form the image of the oscillating system? Would any time averaged fringes form at all? And if they would form how could they be interpreted? The presented study of applicability of geometric moire for dynamical systems answers to these basic questions. It is shown that time average geometric moire can be effectively applied for analysis of meso-, micro- and even nano-scale dynamical systems. Moreover, these techniques are developed for analysis of chaotic oscillations and generalised for stochastic systems and super moire applications.

SPECIAL SESSION: Finite element simulation of the high risk constructions, experiences and problems

Chair: Dubravka Mijuc, Stevan Maksimovic

Tuesday, November 21, 2006

SESSION: Advances in Theoretical Mechanics

Chair: Juan Antonio Lopez Molina

SESSION: Numerical Methods & Experimental Techniques I

Chair: Bernhard Schrefler, John Anagnostopoulos

SESSION: Kinematics & Dynamics

Chair: Sorin Vlase

SESSION: Machine Design & Vibrations

Chair: Constantin Marin

Wednesday, November 22, 2006

SESSION: Dynamics, Turbulence & Fluid Flow

Chair: Takaharu Tanaka

SESSION: Heat and Mass Transfer

Chair: Mohammad hassan Kayhani

SESSION: Numerical Methods & Experimental Techniques II

Chair: Minvydas Ragulskis. Costas Providakis

SESSION: Structural Mechanics & Composite Materials

Chair: Leonardo Pagnotta

SESSION: Computational Methods and Optimization II

Chair: Michael Resch