Computational Fluid Dynamics (CFD) - Modelling Fluid Flow

The Health and Safety Laboratory (HSL) computational modelling specialists are able to offer numerical analysis across a broad spectrum of fluid flow problems, including substantial experience in Computational Fluid Dynamics (CFD).

  CFD in occupational hygiene

Hospital Acquired Infection (HAI)

Predicted trajectories of micro-organisms emitted from a patient in a bronchoscopy suite

HAI is an issue of increasing concern as the potential risk to in-patients, visitors and clinical staff is now more widely acknowledged.

HSL examined factors which influence HAI, such as work practices, ventilation and room design in a bronchoscopy suite at a large teaching hospital.

HSL combined its in-house expertise of advanced microbial detection techniques, occupational hygiene assessment, ventilation measurement and mathematical modelling to study treatment areas in several hospitals.

CFD was employed to identify the possible transport paths of airborne pathogens.

  Case study

Fire and Smoke Movement
Increasing use is being made of CFD in safety cases to predict smoke movement from fires. However, validation of CFD for this application is limited.

HSL have undertaken a programme of experiments and CFD modelling to improve understanding of the capabilities of CFD for the prediction of smoke movement in complex enclosed spaces. Different CFD modelling approaches commonly employed by fire safety engineers were compared and assessed and a series of small-scale experiments, designed to quantify the accuracy of CFD in predicting the transport of smoke in complex geometries, were performed.

CFD modelling approaches were also assessed by application to real fire scenarios, such as on an offshore platform, a building under construction and in an underground train station.

High Pressure Gas Releases
Releases due to failure of underground gas-transmission pipelines can lead to complex flows with the potential to form large flammable gas clouds.

Simple models cannot model all of the necessary interactions. However, CFD can simultaneously model many of the important phenomena associated with high pressure gas releases, for example: impingement of two sonic jets on each other, combined jets impinging on a crater wall, entrainment of ambient air, and interaction with the ambient windfield.

HSL has undertaken a series of support projects looking at the effects of failures in underground gas-transmission pipelines.

Chlorine Dispersion
The release of chlorine from a water treatment works presents the possibility of a major offsite hazard.

HSL was employed on a major Quantitative Risk Assessment (QRA) study of chlorine releases from water treatment works. A CFD approach was used, specifically to take account of the effects of buildings and mountainous terrain on the dispersion behavior. A flat terrain model would predict that the nearest off-site buildings could be enveloped by the cloud. However, the CFD model shows that the complex topography has a dramatic effect; in certain weather conditions the cloud is diverted away from these tall buildings.

The findings from HSL's CFD study have been combined with wind tunnel modelling to produce a major re-appraisal of the risk of chlorine releases.

• Dispersion of accidental releases of toxic gases or aerosol clouds.
• Occupational releases of hazardous substances.
• Movement of airborne micro-organisms.
• Build-up of flammable gas clouds.
• High pressure releases from failed pipelines.
• Smoke movement within buildings.
• Blast Waves.
• Liquid Spills.
• Fires and Explosions.
• Liquid Sprays.
• Shallow Layer Modelling.
• Integral Methods.

In addition, HSL can offer an independent assessment of fluid flow modelling, or models, which have been undertaken or developed by third parties.

Further Details
Contact our Business Development Unit by telephone (+44) 01298 218218, fax (+44) 01298 218822 or email hslinfo@hsl.gov.uk.

  Back to the top