|Tipo di tesi||Tesi di dottorato di ricerca|
|Autore||LEONFORTE, ADRIANO DAVIDE SERAFINO|
|Titolo||Flussi turbolenti attorno a corpi tozzi allungati.|
|Titolo in inglese||Turbulent flows around elongated bodies.|
|Settore scientifico disciplinare||ING-IND/10 - FISICA TECNICA INDUSTRIALE|
|Corso di studi||INGEGNERIA DELL'INNOVAZIONE INDUSTRIALE|
|Data inizio appello||2017-05-17|
|Disponibilità||Accessibile via web (tutti i file della tesi sono accessibili)|
Questo lavoro di tesi riguarda questioni di ampio respiro ancora in corso di dibattito nel campo della fluidodinamica e dell’aerodinamica di corpi tozzi. Lo studio rappresenta pertanto un contributo di potenziale impatto per diverse comunità scientifiche.
This work deals with wide-ranging issues in the field of fundamental fluid mechanics and aerodynamics of bluff bodies. The study thus represents a contribution with a potential impact on different scientific communities. The fluid mechanics community is interested into the characterization of the phenomenology behind flows around elongated bodies. In particular, how free shear flows, impinging flows and wake flows interact is of relevant importance. The type of turbulent structures and the triggering mechanisms of the self-sustaining cycle of turbulence represent also relevant topics. The wind and civil engineering community is also interested in this kind of research activity. Indeed, the flow around finite blunt bodies represents a benchmark for the understanding of the main physical phenomena appearing in a wide range of bluff bodies like, among others, long-span bridge decks and high-rise buildings. Notwithstanding the general interest, the study of this canonical flow encountered several problems both from an experimental and numerical point of view. In experiments the difficulties are related to measurement errors such as the low sampling frequency of optical methods (PIV, particle image velocimetry) and the poor spatial resolution of hot-wire anemometry. Furthermore, experiments suffer from the imperfect control of the boundary conditions which strongly influence the behaviour of such a flow. As an example, an imperfect alignment of the blunt plate with the free-stream, the blockage effect of the wind tunnel and the edge effects due to the finite spanwise dimension of the experiment, are known to significantly affect the behaviour of the flow. On the other hand, the numerical approach is hindered by the high computational costs required to solve the problem in conditions relevant to the applications, i.e. to capture the whole turbulent spectrum at relatively large Reynolds numbers. For this reason, most of the numerical attempts made so far used modelling approaches, thus reducing the accuracy of the solution. In this context, the aim of the present thesis is to perform a Direct Numerical Simulation (DNS) of the flow around a finite blunt body at moderate Reynolds number. This approach allows us to produce high fidelity numerical data, at a value of the Reynolds number at which all the relevant turbulent phenomena occurring in this kind of flow can be detected. The extracted data are then analysed in detail to provide a complete description of the flow and an insight in the observed mechanisms of generation and self-sustainment of turbulence, which has not been performed yet for this kind of flows, and to this level of detail. Results are also expected to be useful for model development and benchmarking.