Validity of thermally-driven small-scale ventilated filling box models

Partridge, Jamie; Linden, P. F.

doi:10.1007/s00348-013-1613-4

Cited by 12 publications

(8 citation statements)

References 14 publications

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“…The tanks boundaries were a composite construction, similar to double glazing, with a 1 cm air gap sandwiched between two 1.25 cm acrylic panels, this construction was designed to minimise unwanted heat loss through the fabric of the enclosure. The tank was previously used, without the heated floor, in the study of Partridge and Linden (2013) to replicate the results of higher Péclet number, saline plumes where the role of heat loss through the enclosure was found to be negligible. For…”

Section: Experimental Set-upmentioning

confidence: 99%

Steady flows in a naturally-ventilated enclosure containing both a distributed and a localised source of buoyancy

Partridge

Linden

2017

Building and Environment

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We consider the flows and stratification established in a naturallyventilated enclosure containing both localised and distributed sources of buoyancy. In this study, both the localised and distributed sources originate from the same horizontal plane, with both adding buoyancy to the enclosure, i.e. representing a point source of heat and a horizontally distributed source of heat at the base of a room. An important parameter controlling the transient and steady states of the enclosure is the ratio of the source buoyancy fluxes ψ = B D B L , with BD and BL the source buoyancy flux of the distributed and localised source, respectively. We examine the role of entrainment between the layers, due to turbulent mixing, and construct a mathematical model to predict the stratification within the room for a range of ψ. We also show that for large ψ and opening areas the two-layer nature of the flow breaks down and there is a short circuit that allows the incoming air to escape through the upper opening without interacting with the full volume of the space. The validity of this model and its break down as predicted by a critical Richardson number are verified against small-scale experiments and the consequences for real-world buildings are discussed.

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Section: Experimental Set-upmentioning

confidence: 99%

Steady flows in a naturally-ventilated enclosure containing both a distributed and a localised source of buoyancy

Partridge

Linden

2017

Building and Environment

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“…Princevac 2010;Pournazeri et al 2012;Cruz-Salas et al 2014;Neophytou et al 2014;Karra et al 2017) or water tank experiments (e.g. Linden et al 1990Linden et al , 1999Hunt and Linden 1999;Bolster and Linden 2007;Livermore and Woods 2007;Yu et al 2007;Tapsoba et al 2007;Kang and Lee 2008;Morsing et al 2008;Chen 2009;Etheridge 2011;Thomas et al 2011;van Hooff et al 2012a,b;Partridge and Linden 2013;Khayrullina et al 2017). Each approach has its specific advantages and disadvantages.…”

Section: Introductionmentioning

confidence: 99%

LES over RANS in building simulation for outdoor and indoor applications: A foregone conclusion?

2018

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Large Eddy Simulation (LES) undeniably has the potential to provide more accurate and more reliable results than simulations based on the Reynolds-averaged Navier-Stokes (RANS) approach. However, LES entails a higher simulation complexity and a much higher computational cost. In spite of some claims made in the past decades that LES would render RANS obsolete, RANS remains widely used in both research and engineering practice. This paper attempts to answer the questions why this is the case and whether this is justified, from the viewpoint of building simulation, both for outdoor and indoor applications. First, the governing equations and a brief overview of the history of LES and RANS are presented. Next, relevant highlights from some previous position papers on LES versus RANS are provided. Given their importance, the availability or unavailability of best practice guidelines is outlined. Subsequently, why RANS is still frequently used and whether this is justified or not is illustrated by examples for five application areas in building simulation: pedestrian-level wind comfort, near-field pollutant dispersion, urban thermal environment, natural ventilation of buildings and indoor airflow. It is shown that the answers vary depending on the application area but also depending on other-less obvious-parameters such as the building configuration under study. Finally, a discussion and conclusions including perspectives on the future of LES and RANS in building simulation are provided.

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“…The reported values of these experimental investigations are tabulated in Linden (2000) and Carazzo et al (2006) with the generally accepted value under the 'top-hat' assumption, in which plume properties are assumed to be uniform inside the plume and zero outside, being around α ≈ 0.13. Comparisons between single-diffusive plumes driven by temperature or solute concentration differences show that, despite orders of magnitude difference in the molecular diffusivity κ of the scalar (in the case of heat or a solute in water, the values of κ differ by a factor of the order of 100), for high-Péclet-number Pe = WL/κ turbulent single-diffusive plumes the rate of entrainment is a constant (Partridge & Linden 2013).…”

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confidence: 99%