Simulation of airflow in one- and two-room enclosures containing a fire source

Stavrakakis, G.; Markatos, N.C.

doi:10.1016/j.ijheatmasstransfer.2007.10.046

Cited by 39 publications

(11 citation statements)

References 32 publications

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“…Results analyzed by Chow and Zou are similar to experimental results deduced by Nakaya et al. The airflow of the two-room's enclosure was analyzed by the various CFD (Stavrakakis and Markatos, 2009). The performances of the turbulence models using correlation equations proposed by Nakaya et al and Chow and Zou were tested.…”

Section: Introductionsupporting

confidence: 69%

Flow Coefficients of Doorway Flow Field in Two-room Building Fires

Ju¹,

Kim²

2012

Journal of Korean Society of Hazard Mitigation

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In the case of a fire of two-room's enclosure, the inflow and outflow mass rates through the doorway located between a burn room and an adjacent room have been researched. The objective of this study are to calculate the flow rates through the doorway of the burn room, to study the inflow and outflow coefficients of the doorway, and accurately to predict the neutral-plane height from the floor of the room in the stratified fire cases of the two-room's enclosure. The inflow and outflow mass rates are analyzed by FDS developed by the National Institute of Standard and Technology, USA. The analyzed results by FDS are compared with the experimental results performed by Nakaya et al. By our study it is known that the flow coefficients vary according to fire size and opening configuration and the mean values of the inflow and outflow coefficients are 0.8 and 1.0 respectively.

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Section: Introductionsupporting

confidence: 69%

Flow Coefficients of Doorway Flow Field in Two-room Building Fires

Ju¹,

Kim²

2012

Journal of Korean Society of Hazard Mitigation

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“…1 for mass continuity, and ux,uy,uz for velocity components in the x , y , z directions, respectively; Γϕ the ‘effective’ exchange coefficient of variable φ , and its expressions for momentum and mass conservation may be found in Ref. 25; and, S φ the source/sink term of variable φ . The assumptions adopted are: (1) incompressible, single-phase and isothermal flow of a Newtonian fluid, (2) steady-state conditions and (3) Richards–Hoxey assumptions concerning the ABL.…”

Section: Mathematical Modellingmentioning

confidence: 99%

Modified ‘closure’ constants of the Standard k–ε turbulence model for the prediction of wind-induced natural ventilation

Stavrakakis

Tomazinakis

Markatos

2011

Building Services Engineering Research and Technology

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In this study, wind-driven natural ventilation in buildings is investigated by means of computational fluid dynamics. The airflow in and around three pilot buildings, which correspond to the most common natural-ventilation designs, i.e. cross-, windward-and leeward-single-sided ventilation, is simulated by applying both the Standard and a modified k-" turbulence model. The latter represents a Prandtl number-modified version of the Standard k-" model, based on the flow-variable (velocity and turbulence variables) distributions and on the atmospheric boundary layer (ABL) assumptions. Numerical results of streamwise and vertical velocity components, as well as of pressure coefficients at the facades, obtained by both turbulence models are compared with available wind tunnel experimental data found in literature. It is concluded that both models applied are in acceptable agreement with measurements, especially for the mean streamwise velocity component, while the proposed modified model is more accurate as far as flow within the windward and the internal parts (i.e. within the building) of the domain is concerned. Practical application: This study focuses on the development of a modified k-" turbulence model for the prediction of wind-driven natural ventilation. The analysis described represents a methodology to produce 'closure' parameters, such as Prandtl numbers, compatible with the incoming wind characteristics (ABL). It was found that for all ventilation cases studied, i.e. cross-and single-sided ventilation, the proposed modified model is more accurate compared with the Standard k-" model, and it accounts for the dumping effect near the walls and for kinetic energy reduction in the impinging region adequately. It is satisfying that the modified k-" model leads to acceptable engineering results within relatively practical computer resources. NomenclatureA Cintegration constants C 1 , C 2 , C empirical constants in k and " equations H b building height (m) k turbulence kinetic energy (m 2 =s 2 ) k f free-stream kinetic energy (m 2 =s 2 ) NEL total number of experimental locations n ! normal-to-surface vector P pressure (Pa) P H b pressure value at the building height (Pa) P k kinetic-energy production rate (Pa=s) Downloaded from RMSE root-mean-squared error RMSE weighted-average value of RMSE RMSE pos RMSE value along the vertical origin located at the position pos S mean rate of strain S " dissipation-rate source term S k kinetic-energy source term S ' source term in the conservation equation u velocity magnitude (m=s) u ! velocity vector u 0 fluctuating velocity (m=s) u Ã friction-velocity magnitude (m=s) u H b wind speed at the building height (m=s) u i velocity component in i direction (m=s) u j velocity component in j direction (m=s) u x , u y , u z velocity components in Cartesian coordinates (m=s) u ref reference velocity (m=s) w pos1 À w pos10 interest factors (weights) participating in the RMSE equation x i spatial component in i direction x j spatial component in j direction y þ dimensionless distance o...

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“…Three-dimensional turbulent airflow is given by Reynolds averaged Navier-Stokes equations (RANS) [14][15][16][17][18][19]. The governing flow equations are shown in Table 2 and solved with the SIMPLE algorithm [20].…”

Section: Description Of Cfd Simulationmentioning

confidence: 99%

Measurement and evaluation of the summer microclimate in the semi-enclosed space under a membrane structure

Hoyano

2010

Building and Environment

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Simulation of airflow in one- and two-room enclosures containing a fire source

Cited by 39 publications

References 32 publications

Flow Coefficients of Doorway Flow Field in Two-room Building Fires

Flow Coefficients of Doorway Flow Field in Two-room Building Fires

Modified ‘closure’ constants of the Standard k–ε turbulence model for the prediction of wind-induced natural ventilation

Measurement and evaluation of the summer microclimate in the semi-enclosed space under a membrane structure

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