CFD Modelling

IRESC uses CFD tools to provide evidence to show and understand the physical phenomena associated with our clients’ facilities. IRESC supports clients in implementing a creative design process to obtain optimal solutions and thereby achieving significant cost savings and risk reduction.

CFD studies are carried out as per UK HSE, OSHA, NORSOK guidelines or any other relevant standard as per client requirement, using industry standard software such as FLACS, KFX and ANSYS CFX. IRESC regularly supports its clients by performing the following types of safety studies:

  • Detailed Probabilistic Explosion Risk Analysis including ventilation, dispersion and explosion simulations
  • Deterministic (consequence based) Explosion Analysis
  • Exhaust Gas Dispersion Study
  • Thermal Plume Dispersion Study
  • Toxic Gas Dispersion Study
  • Helideck Impairment Study
  • Stagnant Zone Analysis
  • Smoke and Gas Ingress Analysis
  • Detailed Probabilistic Fire Risk Analysis including Jet and Pool Fire scenarios
  • Deterministic (consequence based) Fire Analysis for Jet and Pool Fires
  • Passive Fire Protection Optimization Analysis for Vessels
  • Fire and Gas Detector Mapping Study
  • Optimization Study of Blast Relief Panel Area and Location
  • Deflagration to Detonation Transition (DDT) prediction combined with Missile Effect Analysis
  • Incident Investigation Study – act as expert advisors and provide assistance in relation to incidents involving formal HSE proceedings/investigations.

Explosion Modelling

IRESC provides Dimensioning or Design Accidental Load (DAL) on primary structural members and Safety Critical Elements (SCE) of the facility as per NORSOK Z-013, UK HSE guidelines or any other relevant standard. This study accounts for physical factors such as:

  • 3D geometry (congestion and/or confinement) on ventilation, dispersion and explosion events in the facility;
  • Detailed wind rose in the region;
  • Time varying hydrocarbon release rates for 9 different hole sizes
  • Different release directions and release frequencies;
  • Cloud build up rate;
  • Various flammable gas cloud locations, shapes, sizes and reactivity;
  • Various ignition locations and ignition probabilities to obtain the overpressure exceedance curve.

IRESC’s ERA methodology, which has been published in the Journal of Loss Prevention in Process Industry, uses time varying release rates in CFD simulations, which helps in:

  • improved accuracy in predicting tansient flammable gas cloud sizes
  • steeper exceedance curves
  • reduction in DAL values

Ventilation and Dispersion Modelling

IRESC carries out ventilation and dispersion modelling studies using industry standard CFD tools such as FLACS and ANSYS CFX. Full three-dimensional simulations are performed to asses impairment of regions of interest, taking into account effects such as the congestion and blockage in the geometry and complex terrain features, if any, combined with exhaust/toxic gas release rate, release direction and wind condition.

Depending on the study, IRESC supports its clients through CFD based dispersion modelling in the following studies:

  • Helideck Turbulence and Impairment Analysis following CAP 437 criteria.
  • Impairment of outdoor working environment based on OSHA guidelines of 8 hour time weighted average and short term exposure limits of toxic and/or exhaust gases.
  • Impairment due to fugitive emissions as per IP15, ISO 15138, NORSOK-H001 or other relevant standard

Fire Modelling

IRESC provides Dimensioning or Design Accidental Load (DAL) Heat Doses and Fire Durations of the DAL fire in all the fire zones of a facility. This is based on three-dimensional CFD simulations of jet and pool fire scenarios in KFX software. The heat loads on structural elements and target vessels are used in Finite Element Analysis and time-to failure calculations for vessels/ piping.

IRESC fire modelling studies helps clients optimize PFP requirements and reduce costs, whilst also improving mitigation and control of fires equal to or smaller than the DAL fire. If you would like to know more about our expertise in using CFD tools in risk assessment and other safety studies, please contact us at