Skip to main content Accessibility help

Control of light gas releases in ventilated tunnels

  • L. Jiang (a1), M. Creyssels (a1), G. R. Hunt (a2) and P. Salizzoni (a1)


The release of buoyant harmful gases within enclosed spaces, such as tunnels and corridors, may engender specific health, industrial and transportation risks. For safety, a simple ventilation strategy for these spaces is to impose a flow along the tunnel, whose velocity is defined as ‘critical’, that confines the front of harmful buoyant gases immediately downstream of the source of emission. Determining the critical velocity as a function of the geometrical and dynamical conditions at the source is a fundamental fluid mechanics problem which has yet to be elucidated; this problem concerns the dynamics of non-Boussinesq releases relating to large differences between the densities of the buoyant and the ambient fluids. We have investigated this problem theoretically, by means of a simplified model of a top-hat plume in a cross-flow, and in complementary experiments by means of tests in a reduced-scale ventilated tunnel, examining releases from circular sources. Experimental results reveal: (i) the existence of two flow regimes depending on the plume Richardson number at the source $\unicode[STIX]{x1D6E4}_{i}$ , one for momentum-dominated releases, $\unicode[STIX]{x1D6E4}_{i}\ll 1$ , and a second for buoyancy-dominated releases, $\unicode[STIX]{x1D6E4}_{i}\gg 1$ , with a smooth transition between the two; and (ii) the presence of relevant non-Boussinesq effects only for momentum-dominated releases. All these features can be conveniently predicted by the plume-based model, whose validity is, strictly speaking, limited to releases issuing from ‘small’ sources in ‘weak’ ventilation flows. Analytical solutions of the model are generally in good agreement with the experimental data, even for values of the governing parameters that are beyond the range of validity for the model. The solutions aid to clarify the effect of the source radius, and reveal interesting behaviours in the limits $\unicode[STIX]{x1D6E4}_{i}\rightarrow 0$ and $\unicode[STIX]{x1D6E4}_{i}\rightarrow \infty$ . These findings support the adoption of simplified models to simulate light gas releases in confined ventilated spaces.


Corresponding author

Email address for correspondence:


Hide All
Arya, S. P. S. & Lape, J. F. J. 1990 A comparative study of the different criteria for the physical modelling of buoyant plume rise in a neutral atmosphere. Atmos. Environ. 24, 289295.
Aubry, T. J., Jelline, A. M., Carazzo, C., Gallo, R., Hatcher, K. & Dunning, J. 2017 A new analytical scaling for turbulent wind-bent plumes: comparison of scaling laws with analog experiments and a new database of eruptive conditions for predicting the height of volcanic plumes. J. Volcanol. Geotherm. Res. 343, 233251.
Barnett, S. J. 1993 A vertical buoyant jet with high momentum in a long ventilated tunnel. J. Fluid Mech. 252, 279300.
van den Bremer, T. S. & Hunt, G. R. 2010 Universal solutions for Boussinesq and non-Boussinesq plumes. J. Fluid Mech. 644, 165192.
Carazzo, G., Kaminski, E. & Tait, S. 2006 The route to self-similarity in turbulent jets and plumes. J. Fluid Mech. 547, 137148.
Carlotti, P. & Hunt, G. R. 2017 An entrainment model for lazy turbulent plumes. J. Fluid Mech. 811, 682700.
Craske, J. & van Reeuwijk, M. 2015 Energy dispersion in turbulent jets: Part 1. Direct simulation of steady and unsteady jets. J. Fluid Mech. 763, 500537.
Craske, J., Salizzoni, P. & van Reeuwijk, M. 2017 The turbulent Prandtl number in a pure plume is 3/5. J. Fluid Mech. 822, 774790.
Devenish, B. J., Rooney, G. G., Webster, H. N. & Thomson, D. J. 2010 The entrainment rate for buoyant plumes in a crossflow. Boundary-Layer Meteorol. 134, 411439.
Ezzamel, A.2011 Free and confined buoyant flows. PhD thesis, Imperial College London – Ecole Centrale de Lyon.
Ezzamel, A., Salizzoni, P. & Hunt, G. R. 2015 Dynamical variability of axisymmetric buoyant plumes. J. Fluid Mech. 765, 576611.
Grant, G. B., Jagger, S. F. & Lea, C. J. 1998 Fires in tunnels. Phil. Trans. R. Soc. Lond. A 356, 28732906.
Hewett, T. A., Fay, J. A. & Hoult, D. P. 1971 Laboratory experiments of smokestack plumes in a stable atmosphere. Atmos. Environ. 5 (9), 767789.
Hoult, D. P., Fay, J. A. & Forney, L. J. 1969 A theory of plume rise compared with field observation. J. Air Pollut. Control Assoc. 19, 585590.
Hunt, G. R. & Kaye, N. B. 2005 Lazy plumes. J. Fluid Mech. 533, 329338.
Hunt, J. C. R. 1991 Industrial and environmental fluid mechanics. Annu. Rev. Fluid Mech. 23, 141.
Jiang, L., Creyssels, M., Mos, A. & Salizzoni, P. 2018 Critical velocity in ventilated tunnels in the case of fire plumes and densimetric plumes. Fire Safety J. 101, 5362.
Jirka, G. H. & Harleman, D. R. F. 1979 Stability and mixing of a vertical plane buoyant jet in confined depth. J. Fluid Mech. 94 (02), 275304.
Kaye, N. B. & Hunt, G. R. 2007 Overturning in a filling box. J. Fluid Mech. 576, 297323.
Le Clanche, J., Salizzoni, P., Creyssels, M., Mehaddi, R., Candelier, F. & Vauquelin, O. 2014 Aerodynamics of buoyant releases within a longitudinally ventilated tunnel. Exp. Therm. Fluid Sci. 57, 121127.
Manins, P. C. 1979 Turbulent buoyant convection from a source in a confined region. J. Fluid Mech. 91, 765781.
Marjanovic, G., Taub, G. N. & Balachandar, S. 2017 On the evolution of the plume function and entrainment in the near-source region of lazy plumes. J. Fluid Mech. 830, 736759.
Marro, M., Salizzoni, P., Cierco, F. X., Korsakissok, I., Danzi, E. & Soulhac, L. 2014 Plume rise and spread in buoyant releases from elevated sources in the lower atmosphere. Environ. Fluid Mech. 55, 5057.
Michaux, G. & Vauquelin, O. 2008 Solutions for turbulent buoyant plumes rising from circular sources. Phys. Fluids 20, 066601.
Morton, B. R., Taylor, G. & Turner, J. S. 1956 Turbulent gravitational convection from maintained and instantaneous sources. Proc. R. Soc. Lond. A 234, 123.
Oka, Y. & Atkinson, G. T. 1995 Control of smoke flow in tunnel fires. Fire Safety J. 25, 305322.
van Reeuwijk, M., Salizzoni, P., Hunt, G. R. & Craske, J. 2016 Turbulent transport and entrainment in jets and plumes: A DNS study. Phys. Rev. Fluids 1, 074301.
Ricou, F. P. & Spalding, D. B. 1961 Measurements of entrainment by axisymmetrical turbulent jets. J. Fluid Mech. 11, 2132.
Robins, A. G., Apsley, D. D., Carruthers, D. J., McHugh, C. A. & Dyster, S. J.2009 Plume rise model specification, Tech. Rep., University of Surrey, National Power and CERC.
Rooney, G. G. & Linden, P. F. 1996 Similarity considerations for non-Boussinesq plumes in an unstratified environment. J. Fluid Mech. 318, 237250.
Salizzoni, P., Creyssels, M., Jiang, L., Mos, A., Mehaddi, R. & Vauquelin, O. 2018 Influence of source conditions and heat losses on the upwind back-layering flow in a longitudinally ventilated tunnel. Intl J. Heat Mass Transfer 117, 143153.
Suzuki, Y. J. & Koyaguchi, T. 2015 Effects of wind on entrainment efficiency in volcanic plumes. J. Geophys. Res. 120 (9), 61226140.
Thomas, P. H.1968 The movement of smoke in horizontal passages against an air flow, Fire Research Note 723, Fire Research Station.
Vauquelin, O. 2008 Experimental simulations of fire-induced smoke control in tunnels using a helium reduced scale model: principle, limitations, results and future. Tunn. Undergr. Sp. Technol. 23, 171178.
Woodhouse, M. J., Hogg, A. J., Phillips, J. C. & Sparks, R. S. J. 2013 Interaction between volcanic plumes and wind during the 2010 Eyjafjallajökull eruption, Iceland. J. Geophys. Res. 118 (1), 92109.
Woods, A. W. 1997 A note on non-Boussinesq plumes in an incompressible stratified environment. J. Fluid Mech. 345, 347356.
Wu, Y. & Bakar, M. Z. A. 2000 Control of smoke flow in tunnel fires using longitudinal ventilation systems – a study of the critical velocity. Fire Safety J. 35 (4), 363390.
MathJax is a JavaScript display engine for mathematics. For more information see

JFM classification

Control of light gas releases in ventilated tunnels

  • L. Jiang (a1), M. Creyssels (a1), G. R. Hunt (a2) and P. Salizzoni (a1)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed