CFD simulations on high-buoyancy gas dispersion in the wake of an isolated cubic building using steady RANS model and LES

Lin, Chao; Ooka, Ryozo; Kikumoto, Hideki; Sato, Taiki; Arai, Masato

doi:10.1016/j.buildenv.2020.107478

Cited by 17 publications

(4 citation statements)

References 54 publications

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“…A higher Sct-number, which means lower diffusion in order to compensate for the overestimation, led to more accurate concentrations. Chao Lin et al [17] came to the same conclusion when analyzing high-buoyancy gas dispersion with the RANS model. As another telling example, Tominage et al [18] also found a high discrepancy (three to five times) between the RANS model and the measurement when modeling pollution dispersion in a street canyon.…”

Section: Influence Of the Sct-numbermentioning

confidence: 66%

On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB

Doumbia

Janke

et al. 2021

Applied Sciences

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The tracer gas method is one of the common ways to evaluate the air exchange rate in a naturally ventilated barn. One crucial condition for the accuracy of the method is that both considered gases (pollutant and tracer) are perfectly mixed at the points where the measurements are done. In the present study, by means of computational fluids dynamics (CFD), the mixing ratio NH3/CO2 is evaluated inside a barn in order to assess under which flow conditions the common height recommendation guidelines for sampling points (sampling line and sampling net) of the tracer gas method are most valuable. Our CFD model considered a barn with a rectangular layout and four animal-occupied zones modeled as a porous medium representing pressure drop and heat entry from lying and standing cows. We studied three inflow angles and six combinations of air inlet wind speed and temperatures gradients covering the three types of convection, i.e., natural, mixed, and forced. Our results showed that few cases corresponded to a nearly perfect gas mixing ratio at the currently common recommendation of at least a 3 m measurement height, while the best height in fact lied between 1.5 m and 2.5 m for most cases.

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Section: Influence Of the Sct-numbermentioning

confidence: 66%

On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB

Doumbia

Janke

et al. 2021

Applied Sciences

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“…Indeed, in terms of building wake estimation, the RANS calculation is generally considered not able to reproduce bluff body wake flow accurately. The building wake size is more likely to be overestimated [35,36].…”

Section: Mean Wake Deflection Phenomenonmentioning

confidence: 99%

Wake of Elongated Low-Rise Building at Oblique Incidences

Wang

Lam

2021

Atmosphere

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We investigated the turbulent wake of an elongated low-rise building at oblique wind incidence via wind tunnel experiments and numerical simulations. The deflection phenomenon of mean building wake is clearly supported by the downwind trajectory of the point of maximum velocity deficit. A two-step mechanism is proposed for the understanding of the wake deflection process and its evolution in the building wake. The oblique wind incidence leads to a location shift of shear layer flow competition in the near-wake region (“WD1”) and then the deflected prevailing wind extends its effect in the far-wake region (“WD2”). The streamwise development of lateral wake deflection predicted from this mechanism, as well as the variations with height due to the three-dimensional wake structure, compares well with the measurement and simulation results. For aviation safety assessment of wake effect of the present building on aircraft landing, the data are compared to the “1:35 rule” and “7-knot criterion”. In addition, the importance of velocity fluctuation is demonstrated with an exceedance probability analysis.

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“…In the CFD technique, Reynolds-averaged Navier-Stokes (RANS) models [15] and large-eddy simulation (LES) [5,10,13] are frequently used to represent for barrier effects. In urban environments with complicated flow fields, LES has shown more accurate prediction accuracy on airflow and pollutant dispersion than the RANS model [25,26].…”

Section: Introductionmentioning

confidence: 99%

Large-eddy simulations on pollutant reduction effects of road-center hedge and solid barriers in an idealized street canyon

Lin

Ooka

Kikumoto

et al. 2023

Building and Environment

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CFD simulations on high-buoyancy gas dispersion in the wake of an isolated cubic building using steady RANS model and LES

Cited by 17 publications

References 54 publications

On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB

On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB

Wake of Elongated Low-Rise Building at Oblique Incidences

Large-eddy simulations on pollutant reduction effects of road-center hedge and solid barriers in an idealized street canyon

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