Martin Prignon, a doctoral student from the faculty of Architecture, Architectural Engineering and Urban Planning (LOCI) at Université Catholique de Louvain (UCL), is studying air-leakage through cracks in buildings. One of the objectives of his PhD is to analyze the amount of air that would be lost in cracks at the edges of window frames, for a given pressure-difference. He plans to model this experimentally by setting up an airtight chamber with a fan at one end and the crack at the other end. These experiments are possible thanks to his collaboration with Entreprises Jacques Delens (EJD), a construction and development company in Brussels (Belgium). EJD is a subsidiary of the BESIX Group, a major international player in the field of construction. As a first step, Martin plans to analyze the flow through the crack in the windows. Later he will move on to other components such as doors, electrical sockets, etc...
Besides performing the experiments, Martin is also modelling them numerically with CFD. For his study, Martin chose to use FINE™/Open with OpenLabs™ which comes with HEXPRESS™, the FINE™/Open flow solver and CFView™ for post-processing.
With the basic CAD functionalities available in HEXPRESS™, he was able to create a basic domain to test the proof of concept with relative ease. Additionally, with the mesh wizard available in HEXPRESS™, he was able to perform easy back-and-forth operations at each step of the meshing process. After generating a good quality mesh, he simulated the flow on FINE™/Open solver and later used CFView™ to analyze the results. He plans to identify the pressure at various points in this domain for various amounts of mass-flow and compare them against the experiment.
Although it looks like a simple flow, the flow through this domain offers a variety of challenges.
- The domain consists of regions of significantly different flow speeds: very low speed (in the inlet cylinder and box in front of the window) and relatively high velocities (in the crack).
- One of the most critical regions is the intersection of the crack with the rest of the domain. The sudden contraction in the area, combined with the vortices forming in that region, create a challenge which is tackled by the FINE™/Open solver.
We wish Martin all the best with his PhD!
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In the next release of FINE™/Open with OpenLabs™, a "Best Practices" on simulating low-speed flows of a similar nature will be included.