Modeling the Diffusion and Advection of Pollutants from Flaring in Iran, Considering Seasonal Atmospheric Variability

Document Type : Original Article

Authors

1 Department of Environmental Engineering, Faculty of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran

2 Department of Water Resources Management, Faculty of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran

Abstract

Gas flaring in oil-producing regions is a significant source of atmospheric pollutants; however, near-field dispersion dynamics governing worker exposure from low-capacity flares under seasonally contrasting atmospheric stability conditions remain insufficiently characterized. This study employed a two-dimensional Eulerian computational fluid dynamics (CFD) framework with RNG k-ε turbulence closure to simulate the dispersion of carbon monoxide (CO), nitrogen oxides (NOx), and sulfur dioxide (SO2) from a representative low-capacity gas flare at exit velocities of 6-7 m/s and combustion temperatures of 900-1200 K. The computational domain, 2050 m × 286 m, was discretized into 66,000 quadrilateral control volumes. Simulations were conducted for two seasonally representative scenarios: an unstable summer atmosphere (Monin-Obukhov length L = −1148 m) and a stable winter surface-layer inversion (L = +364 m). Model predictions were validated against field measurements at three downwind distances, yielding R² values of 0.997, 0.9996, and 0.969 for CO, NOx, and SO2, respectively. CO concentrations at breathing height (2 m) exceeded the regulatory ambient standard by 55.0% in summer and 35.0% in winter; SO2 exceeded the primary ambient standard by 375% and 362.5%, respectively. NOx remained below the flare emission standard at the plume-core level in both seasons. Under unstable summer conditions, buoyancy-driven vertical uplift dominated plume transport; under stable winter conditions, a near-surface recirculation zone between 50 and 400 m downwind generated the widest spatial extent of regulatory exceedance. Atmospheric stability and near-source recirculation are identified as the primary controls on occupational exposure intensity, underscoring the need for targeted flare gas recovery systems and meteorology-aware worker management in Iran's oil-producing regions.

Keywords

Main Subjects

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Civil Engineering and Applied Solutions
Volume 3, Issue 2
April 2027
Pages 1-15

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History

  • Receive Date: 15 April 2026
  • Revise Date: 12 May 2026
  • Accept Date: 16 June 2026
  • First Publish Date: 16 June 2026

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