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CO2 dispersion

CO2-FOAM, a dedicated solver for CO2 dispersion previously developed within the frame of the open source CFD code OpenFOAM® by the authors’ group has been further extended to include the homogeneous relaxation model which is more suited to accountfor the presence of solid CO2 within the release. The code offers both RANS and LES approaches, but only the RANS approach is reported in the present paper. In order to better capture the interaction between the dispersed CO2 and the ABL-specific boundary layer, a compressible form of the k- SST turbulence model is used in conjunction with ABL-specific wall-functions. Predictions have been conducted for Case Study 3 in the COOLTRANS research programme. The CO2 was released through a puncture in a buried pipe. Evaluations of the different variations of the k- SST model suggested that the baseline k- SST model delivered the predictions that more closely matched the experimental measurements for the tests cases considered here. The predictions have achieved reasonable agreement with the data based on a “blind validation”, giving confidence to the capability of CO2FOAM to be used for quantified risk assessment involving far field CO2 dispersions; especially for situations where screen tests with semi-empirical or integral models suggest more detailed consequence analysis. To illustrate the application of the code, further predictions were conducted using the same release conditions as the baseline case but for scenarios involving a commercial building placed with its front face 25 m downwind of the release. The CO2 cloud wraps around and passes the building, generating turbulence as well as large flow oscillations and recirculation zones. The increased turbulence level due to the existence of the building would lead to more intense mixing and contribute to the dilution of the CO2 cloud. This effect is, however, decreased by buoyancy forces as density stratification in the flow tends to suppress turbulence generation. The building has a blocking effect to the flow, where the cloud can be trapped temporarily or diverted towards specific zones.


  1. Jennifer X Wen, Pierre Le Fur, Hongen Jie and V. C. Madhav Rao, Further development and validation of CO2FOAM for the atmospheric dispersion of accidental releases from carbon dioxide pipelines, J of Greenhouse Gas Control, Vol. 52, Sep. 2016, Pages 293-304.
  2. Jennifer Wen, Ali Heidari, Baopeng Xu and Hongen Jie, Dispersion of carbon dioxide from vertical vent and horizontal releases—A numerical study, Proc IMechE Part E:J Process Mechanical Engineering, 227(2) 125–139, IMechE 2013.
  3. Richard Adoua, Pierre Le Fur, Jennifer Wen, The effect of obstacles and terrain on the dispersion of released carbon dioxide, 4th Int. Forum on Transportation of CO2 by Pipeline, June, 2013, Newcastle, UK.
  4. Saturin Adoua, Pierre Le Fur and Jennifer X Wen, The effects of obstacles and terrain on the dispersion of released carbon dioxide, 4th Forum on Transportation of CO2 by Pipeline, 20-21 June 2012, Newcastle, UK.