This subject is relevant to several fields, including (but not limited to) civil, thermal, mechanical and chemical engineering. The project will concentrate on the elaboration of a general computational (CFD) platform.
Most of existing models for the evaluation of heat loss from buildings or industrial plants in cross flow (horizontal wind) are based on empirical correlations and simplified relationships (generally applicable to the case of a single building or power unit). Given the diversity and rich spectrum of circumstances in which multiple buoyant plumes generated by a discrete set of buildings (or heat sources in a power plant) can interact with a cross flow, generalizations are rather difficult and such correlations can be used for first hand calculations only.With this project, we propose an investigation into the complexity of such dynamics over a wide spectrum of conditions (many situations are possible in principle depending on the specific case considered, namely, the distribution in space of heat sources and the properties of the “external” flow). The “receiving” ambient can be characterized by its temperature distribution, velocity profile and boundary conditions, which are not “unique”. The temperature may be constant, display a stable thermal stratification, or even an unstable distribution (leading to the onset of massive thermal convection). In terms of velocity, similarly, the ambient may be in stagnant conditions or support a uniform or sheared flow, which, in turn, can be laminar or turbulent. Moreover, the thermal plumes created by the effects of thermal buoyancy may be steady in mean or completely erratic and apparently unpredictable (plumes can undergo instabilities promoted by the cross flow or thermal buoyancy itself and split into different parts or coalesce and produce large-scale features such as the so-called “heat island effect”). Such dynamics are made even more complex by the occurrence of the so-called “sheltering phenomenon” (given a set of thermal plumes in a crossflow, the leading plume is typically deflected more by the ambient current, while the other (rear) jets are less affected).
Proper analysis of all these effects will require the elaboration of a high-fidelity CFD numerical framework able to predict the effective interplay between localized (thermal) convective features [1,2] and the large-scale flow. This will also require proper assessment, development and implementation of relevant turbulence models, which are generally different with respect to those traditionally used in other contexts (e.g., aerodynamics or hydrodynamics). Starting from relatively simple test cases, the student will progressively consider configurations and problems with an increasing degree of complexity, up to characterizing the complete hierarchy of thermal and fluid-dynamic interactions occurring between the set of buildings (or equivalently the units of an industrial plant) and the environment.
 M. Lappa (2009), “Thermal Convection: Patterns, Evolution and Stability”, 700 pages. - ISBN-13: 978-0-470-69994-2, ISBN-10: 0470699949, John Wiley & Sons, Ltd (2009, Chichester, England).
 M. Lappa (2012), Rotating Thermal Flows in Natural and Industrial Processes, 540 pages., ISBN-13: 978-1-1199-6079-9, ISBN-10: 1119960797, John Wiley & Sons, Ltd (2012, Chichester, England).