CFD and ventilation research

Li, Yuguo; Nielsen, Peter

doi:10.1111/j.1600-0668.2011.00723.x

Cited by 146 publications

(90 citation statements)

References 103 publications

(111 reference statements)

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“…This can be attributed to mixing behaviour previously observed for the NPV system in [12], as opposed to the displacement behaviour of the other three cases.…”

Section: : Indoor Temperature Ranges In Non-winter Months At (A) 100mentioning

confidence: 71%

“…2d). The use of ceiling-based ducts to convey fresh air under buoyancy has already been demonstrated in previous work by Adamu et al, [12] as a novel way of achieving natural personalised ventilation (NPV). The NPV was shown to be natural ventilation equivalent of mechanised PV systems as defined in [21], however, as conceived for this study, the NPV concept can be applied for isolated spaces even if personalised delivery of air to patients is not the goal.…”

Section: Ceiling-based Natural Ventilation Conceptmentioning

confidence: 99%

“…The use of CFD in particular has risen steadily since 2002, especially within the research community, where it has become a major tool for airflow investigations. The wide applicability, acceptability of CFD as a ventilation modelling tool is however tied to its concurrent use with theoretical and experimental models as verification and validation of available codes become increasingly important [12]. This study intends to use (zonal) dynamic thermal model (DTM) as well as CFD modelling as methods of airflow investigation.…”

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confidence: 99%

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Performance evaluation of natural ventilation strategies for hospital wards – A case study of Great Ormond Street Hospital

Adamu

Price

Cook

2012

Building and Environment

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“…This can be attributed to mixing behaviour previously observed for the NPV system in [12], as opposed to the displacement behaviour of the other three cases.…”

Section: : Indoor Temperature Ranges In Non-winter Months At (A) 100mentioning

confidence: 71%

Section: Ceiling-based Natural Ventilation Conceptmentioning

confidence: 99%

mentioning

confidence: 99%

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Performance evaluation of natural ventilation strategies for hospital wards – A case study of Great Ormond Street Hospital

Adamu

Price

Cook

2012

Building and Environment

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“…In addition, several previously published guidelines stated that a grid-sensitivity analysis should be conducted to make sure the results obtained are (nearly) grid independent and do not suffer from excessive amounts of numerical diffusion (e.g. Jones and Whittle 1992;Chen and Srebric 2002;Chen and Zhai 2004;Roache 1997;Li and Nielsen 2011;Blocken 2015). Sørensen and Nielsen (2003) stated that-at that time-obtaining a grid-independent solution for 3D cases was very difficult due to the lack of computational resources.…”

Section: Grid Resolutionmentioning

confidence: 99%

“…In addition, they explicitly mentioned the increased presence of numerical diffusion when the flow direction is not aligned to the wall surface in case of a structured grid. Li and Nielsen (2011) stated that in theory, numerical errors can be limited to an acceptable level when the number of grid points is sufficient and the grid resolution is sufficiently high. In addition, several previously published guidelines stated that a grid-sensitivity analysis should be conducted to make sure the results obtained are (nearly) grid independent and do not suffer from excessive amounts of numerical diffusion (e.g.…”

Section: Grid Resolutionmentioning

confidence: 99%

Low-Reynolds number mixing ventilation flows: Impact of physical and numerical diffusion on flow and dispersion

Hooff

Blocken

2017

Build. Simul.

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Quality assurance in computational fluid dynamics (CFD) is essential for an accurate and reliable assessment of complex indoor airflow. Two important aspects are the limitation of numerical diffusion and the appropriate choice of inlet conditions to ensure the correct amount of physical diffusion. This paper presents an assessment of the impact of both numerical and physical diffusion on the predicted flow patterns and contaminant distribution in steady Reynolds-averaged NavierStokes (RANS) CFD simulations of mixing ventilation at a low slot Reynolds number (Re≈2,500). The simulations are performed on five different grids and with three different spatial discretization schemes; i.e. first-order upwind (FOU), second-order upwind (SOU) and QUICK. The impact of physical diffusion is assessed by varying the inlet turbulence intensity (TI) that is often less known in practice. The analysis shows that: (1) excessive numerical and physical diffusion leads to erroneous results in terms of delayed detachment of the wall jet and locally decreased velocity gradients; (2) excessive numerical diffusion by FOU schemes leads to deviations (up to 100%) in mean velocity and concentration, even on very high-resolution grids; (3) difference between SOU and FOU on the coarsest grid is larger than difference between SOU on coarsest grid and SOU on 22 times finer grid; (4) imposing TI values from 1% to 100% at the inlet results in very different flow patterns (enhanced or delayed detachment of wall jet) and different contaminant concentrations (deviations up to 40%); (5) impact of physical diffusion on contaminant transport can markedly differ from that of numerical diffusion.

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Influence of inlet turbulent condition on the formation mechanism of local scalar concentrations

Yamasawa

Hirayama

Kuga

et al. 2022

Japan Architectural Review

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In the existing ventilation design, the ventilation rate is defined by the time‐averaged flow rate, and the fluctuating (turbulence) component is not typically considered. However, inlet turbulent conditions are also assumed to have some influence on the formation of contaminant distributions. Therefore, the influence of turbulent kinetic energy at the inlet boundary on scalar transportation in an indoor environment needs to be elucidated when discussing the ventilation rate setpoint via the supply inlet in terms of local contaminant concentration control. This study discusses the impact of turbulent kinetic energy in the ventilation design on scalar transfer and its distribution within an enclosed space. To understand the influence of various inlet turbulent boundary conditions on scalar transfer, a computational fluid dynamics analysis was conducted using two different room models: a simple room and a room with a ventilation system that creates a large velocity gradient. The results indicate that scalar transfer within the room is not solely dominated by the averaged velocity input at the inlet boundary but is also strongly affected by the turbulence conditions at the inlet boundary. The numerical results indicate the possibility of a new ventilation design strategy that simultaneously considers the transfer of turbulent components and contaminants.

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CFD and ventilation research

Cited by 146 publications

References 103 publications

Performance evaluation of natural ventilation strategies for hospital wards – A case study of Great Ormond Street Hospital

Performance evaluation of natural ventilation strategies for hospital wards – A case study of Great Ormond Street Hospital

Low-Reynolds number mixing ventilation flows: Impact of physical and numerical diffusion on flow and dispersion

Influence of inlet turbulent condition on the formation mechanism of local scalar concentrations

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