The project
MISTRAL has two main targets: to enrich the scientific knowledge concerning the
aerodynamic behaviour of cylinders characterized by simple cross-sections
(circular and rectangular ones) and to develop the tools that are necessary to
transfer such knowledge to the wind engineering and industrial aerodynamics
communities.
In the
civil engineering field several typologies of structures – as bridge decks,
stay cables, towers and tall buildings – can be idealized as cylindrical bodies
as far as aerodynamic characteristics and behaviour is concerns. As a result,
the products of researches aimed at understanding the aerodynamic behaviour of
cylinders are commonly employed in design practise and are incorporated in
codes for the definition of wind-induced loads.
For some
kind of structures, such as suspended bridges and high-rise buildings, the wind
actions are absolutely the dominant ones. They influence major design choices,
determining the structural organism, as well as the exterior shape. Often, the
wind actions define the limit between the structure that can be constructed and
safely operated, from the ones that cannot be realized. Such a limit moves as
the knowledge improves, enabling realizations that were unconceivable only a
few years ag bridges with extremely long spans like the one designed for the
crossing of the Messina strait, or super-tall buildings like the ones presently
under design or construction in several parts of the world. This scientific and
technologic challenge calls researchers and designers for a deeper
comprehension of the actual physical phenomena taking place, to develop
reliable mathematical models able to describe the aerodynamic actions, the
structural response and their mutual interaction.
MISTRAL
means to tackle this ambitious task by partnering four main research fields:
wind-tunnel tests (A), numerical simulations carried out my means of
computational fluid dynamics (CFD) techniques (B), the analysis and the
interpretation of measured and simulated data through traditional and
innovative mathematical tools (C) and the realization of design-oriented models
capable of representing and simulating aerodynamic. These different research
fields are connected each other as shown in Figure 1.
Both the
wind tunnel tests and the numerical simulations are aimed at the creation of a
large database of aerodynamic measurements, using widely-accepted experimental
and simulation techniques representing the present state-of-the-art in this
field. The fully-innovative contribution of MISTRAL is related with the
development, the validation and the application of tools for representing and
understanding the results of experimental tests and numerical simulations.
Within this scope, largely accepted statistical tools as the Proper Orthogonal
Decomposition (POD) will be used jointly with innovative instruments borrowed
from other scientific contexts as the Independent
Component Analysis (ICA) and the Multi-channel Blind Deconvolution, in such a
way to improve its interpretative abilities and its potentialities for the development
of predictive models for aerodynamic loads. The use of these techniques will
introduce, besides the accepted concept of coherent structure, new concepts like
independent structure and dynamical structure. Such new concepts will enable
the use of the usual POD formal scheme to deal with problems in which it is
well known POD fails.
The
experimental tests and the numerical simulations that will be carried out
within MISTRAL will create a unique database, having no equal worldwide as far
as completeness and methodicalness are concerned. Such database will be made
available for the scientific and technical communities through a dedicated web
platform, to encourage further developments of interpretative and provisional
tools based on coherent and/or independent structures and to enables systematic
comparisons between experimental results and numerical simulations.
Wind tunnel testing is one of the main aspects
in MISTRAL and will entirely be carried in the DICAT – DIFI wind tunnel
facility at the University
of Genova. Such a
facility has been opened in October 2008 after a four-year construction phase technically
supervised by the scientific coordinator of MISTRAL. At present, more than
1.000.000 Euro have been invested in this facility. The scientific coordinator
of MISTRAL co-financed the realization of the wind tunnel with an amount over
100.000 Euro.
During
MISTRAL the instrumentation of the wind tunnel will be largely improved, contributing
to place the laboratory in the forefront of the Italian and international wind-tunnel
network.
MISTRAL is
realized by a single Research Unit established at the Department of Civil,
Environmental and Architectural Engineering (DICAT) of the University of Genova.
Nevertheless, the Research Unit is constituted by researchers with different
cultural formation (as civil and aeronautical engineering) and background in
structural engineering and fluid mechanics, as well as experience in wind
engineering, experimental and computational aerodynamics, vibration mechanics.
In this sense, MISTRAL will create a team able to overcome paradigms
consolidated in specific fields by exchanging interpretative tools and concepts
to produce significant improvements in the scientific knowledge. According to
the spirit of the call “Futuro in Ricerca”, all the researchers involved in
MISTRAL are “young researchers”: the older researcher is the coordinator, who
is 36 year old. Despite their young age, all the members of the research unit
already furnished, in their own fields, a significant scientific contribution
on topics pertaining to the scope of MISTRAL.
The
Scientific Coordinator of MISTRAL was involved in several public and
private-funded research projects concerning wind engineering and bluff-body
aerodynamics; he also cooperates with well-known international scientists
working in these fields, who will be involved as third-part advisors to control
the quality of the obtained results and the correctness of choices operated. The
co-ordination of several private-funded research projects also provided the MISTRAL
Scientific Coordinator with the planning and management capabilities required
for the development of such a complex project.
MISTRAL,
analysing simple cylinders - with circular or rectangular cross-section -
suitably dimensioned in order to highlight different aerodynamic phenomena, clearly
collocates within the context of base research. However, since such simple
structural shapes are very recurrent in civil and industrial structures, the
obtained results can have a significant impact on the definition of wind
actions within national and international codes influencing the common practice,
as well as the scientific community.
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