Nafsika Drosou, a LoLo MRes student recently attended the IBPSA CFD Summer Seminar

Nafsika Drosou, a LoLo MRes student recently attended the IBPSA CFD Summer Seminar
25th June 2012 Alison Parker


The English chapter summer event of the International Building Performance Simulation Association (IBPSA) took place in June 20, 2012 at the Department of Civil, Environmental & Geomatic Engineering of UCL. This well-attended full day affair showcased recent academic and industry work on the applications of Computational Fluid Dynamics (CFD) simulation tools in the built environment. The seminar focused equally on indoor and outdoor environments and was followed by the IBPSA-England General Membership and Board meetings. Aside from CFD practitioners, the audience comprised PhD students in various stages of their research, as well as recent graduates of built environment & sustainability MSc courses who are called to use CFD software in their new posts.

To quote the IBPSA-England poster: “CFD is often used for predicting indoor air quality and temperature distribution inside buildings, especially in cases where natural ventilation is being tested. Common modelling challenges encountered are: accurate specification of boundary conditions; selection of appropriate turbulence model and convergence control.” Additional challenges are incurred when modelling complex outdoor environments for “wind-driven rain on building facades, heat transfer through external building surfaces and air pollutant dispersion around buildings.”

As mentioned by a member of the audience, CFD simulation can be viewed by some as “more of an art than science”, even though CFD software uses complex mathematical equations to solve the physics behind the behaviour of air. For this reason it is critical that CFD is accompanied by analogue experiments for validation (examples are salt baths and wind tunnels for indoor and outdoor studies respectively). This point was stressed by the presenters, as they described their validation efforts, and elicited questions of interest from the audience. Another theme that re-occurred during the day was the largely increased computing power available today, as compared to that of even 5 years ago. Advancement in computer technology has led to an increase in the number of parameters that can be considered in a CFD model, as well as higher speeds in generating simulation results.





The seminar demonstrated a broad range of CFD applications when coupled with other models. Dr Paul Cropper of De Montfort University and Professor Malcolm Cook of Loughborough University combined CFD with the IESD-Fiala thermal comfort model and breathing manikins to spatially predict body surface temperature and quantify thermal comfort predictions. Faisal Durrani of Loughborough University used salt bath modelling to validate buoyancy information and multiple steady states he captured using the Large Eddy Simulation (LES) turbulence model. Dr Ian Eames and his UCL team of researchers, considered CFD along with mathematical models, in order to develop the ACEfem Code which also takes buoyancy and chemistry into account in examining the airborne transmission of disease. Dr Bernardo Vazquez from Buro Happold, presented the Annual Comfort Map (based on CFD and the Lawson Comfort Criteria for wind) used in the early design stage of complex developments and compounds, to indicate the optimum space for each function or activity. Dr Liora Malki-Epshtein and her team from UCL, calibrated the range and accuracy of CFD models by means of the Bayesian statistical model, in order to examine pollutant concentrations and velocities in urban street canyons. Last but not least, Mutlu Ucuncu from Arup described how CFD coupled with dynamic thermal and climate analysis models informed the choice of roof design for a stadium in a hot and arid environment.

Observations made by the coordinators of the event mirrored the escalating uptake of CFD simulation projects in recent years. Dr Liora Malki-Epshtein, host of this year’s event, commented on the noticeable increase in the percentage of women who are interested in CFD projects while IBPSA-England Chair, Professor Malcolm Cook, was struck by the high degree of quality, and difficulty, contained in the questions research students posed to the presenters. As CFD modelling tools continue to gain ground in academic and industry circles, events such as this will be vital for tackling modelling challenges, by means of strengthening the bridges of communication amongst a growing user base. Effectively this will accelerate the evolution of CFD modelling in the built environment and increase its range of applications.

For more information on IBPSA-England:

Article written by Nafsika Drosou, LoLo MRes Student & IBPSA-England Member