Technological Education Institute Piraeus – Τ.Ε.Ι. Πειραιά
The Laboratory of Fluid Mechanics and Heat Transfer belongs to Mechanical Engineering Department of the Technological Education Institute (T.E.I.) Piraeus. The laboratory’s operation is continuous for the last thirty years. Its basic intended target is the theoretical and practical education of students in issues related to the wide area of Thermo-Fluids. It consists of two faculty members, one member for technical support and a group of five high-educated Engineers who are, also, engaged in research, especially in key areas collaborating with similar departments and research groups around the world, in projects related to:
- Advanced CFD and Heat Transfer (e.g. Droplets Evaporation and Collision, Two-Phase Flows and Spray Drying)
- Design and Calculation of Buildings energy needs (e.g. Natural Ventilation, P.C.Ms)
- Applications of CFD and Artificial Neural Networks (ANNs) in fluid flows, air pollutants concentrations in urban area, human thermal comfort-discomfort, etc.
Laboratory’s equipment includes two subsonic wind tunnels, pumps, basic flow experiments hydraulic benches and various instruments for educational/research use. Moreover, the laboratory provides thermal conductivity testing services of insulating materials, according to ISO standards, via the use of certified US and EU Instruments.
The collaboration with SimTec has been started in 2004 and it still continues with great success due to the need of our laboratory to be involved in several research areas via the use of CFD and to attempt to educate our students with high-level engineering tools, such as FLUENT and Flowlab. Since then, with the help of the high-educated staff of SimTec, we have been involved in several research areas, producing more than 30 high-level under- and post-graduate dissertations and 15 publications in journals and conferences.
1. Numerical investigation of a naturally cross-ventilated building
This work deals with the numerical three-dimensional prediction of the induced flow patterns around and inside a building, which is cross-ventilated in a natural way. The air change rate is controlled by two opposite openings on the building envelope, as a function of wind velocity, U∞ and its incidence angle, β. The dimensions of the building’s envelope are 5.56m x 5.56m x 3m, giving a clear volume of 68.95m3. The computational domain used, displayed in Image 1, reproduces the wind tunnel’s dimensions, in which the series of experiments was done. The numerical grid used for all cases examined consists of around 3.2×106 tetrahedral computational cells. The numerical methodology is based on the finite volume numerical solution of the Navier-Stokes equations, using the CFD commercial code FLUENT. The numerical results are compared with available experimental data regarding the refresh rate of the building’s room and the relative velocity profiles at the window openings, indicating a good agreement. Furthermore, a detailed description of the natural ventilation process is provided, by predicting the spatial distribution of air-change rate at two horizontal planes of the building (Image 3), while additional information regarding the time-dependent character of the induced velocity and pressure field inside and outside the building is presented (Image 2); information which cannot be easily extrapolated by experimental methodologies.
2. Numerical investigation of the air pollutant dispersion within the Campus of T.E.I. Piraeus
This work involves the numerical investigation of air pollutant dispersion within urban environment, containing street canyons of different aspect ratios and buildings with a wide variety of different geometries into a real complex three-dimensional geometry; the Campus of the Technological Education Institute (T.E.I.) of Piraeus, Greece. The numerical methodology is based on the finite-volume numerical solution of the Navier-Stokes equations using the CFD commercial code FLUENT, into a three-dimensional computational domain of 300m (length) x 420m (width) x 100m (height) of 5.4 million tetrahedral cells, produced by the upward swept of the faces shown in Image 1. The behaviour of pollutants, emitted by the cars circulating in the roads within the campus, under certain wind values and directions, is investigated. The research was reached in significant conclusions about air pollution dispersion and recognised the most vulnerable areas within the TEI campus, as shown in Image 2 by producing the contours of mole fraction for CO in two different heights and in Image 3, by the corresponding iso-surfaces with values of 2×10-6 (a) and 4×10-6 (b).