- Author
- Patterson, N.
- Title
- Assessing the Feasibility of reducing the Grid Resolution in FDS Field Modelling.
- Coporate
- University of Canterbury, Christchurch, New Zealand
- Report
- Fire Engineering Research Report 02/6, May 2002, 196 p.
- Distribution
- FOR MORE INFORMATION CONTACT: School of Engineering, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. Telephone: 643-364-2250, Fax: 643-364-2758, Website: http://www.civil.canterbury.ac.nz
- Keywords
- field models | zone models | fire models | data analysis | temperature | hangars
- Identifiers
- Fire Dynamics Simulator (FDS); CFAST (Consolidated Fire growth And Smoke Transport)
- Abstract
- Field modelling is increasingly becoming the main form of fire modelling for design purposes. To reduce the computational running time of field models designers are sacrificing fine grid resolution without considering the consequences this could incur on the results. This report aims to provide some validation on the extent to which grid size can be increased in the field model Fire Dynamics Simulator (FDS) before the results are compromised and to determine whether there is a point at which zone model predictions become more reliable. FDS model predictions using a range of grid sizes were compared against two separate sets of experiments: 1. The University of Canterbury McLeans Island tests. These tests were performed using two isorooms, each measuring 2.4 x 3.6 x 2.4 metres. 55kW and 110kW tests were simulated in FDS. 2. The US Navy Hanger tests in Hawaii. The hanger measured 98 x 74 metres x 15 metres high at its apex. Two tests were simulated in FDS. These had Heat Release Rates (HRRs) of 5580kW and 6670kW respectively. The second test had a draft curtain situated centrally around the fire. This was modelled in two different FDS constructions; one simulated the entire hanger, the other only the area of the draft curtain. Simulations using the zone model CFAST were also performed for all the tests outlined above. The comparisons with the McLeans Island Tests showed that FDS models with grids of 150mm (H/16) made temperature predictions as accurate as 100mm (H/24) grid models, generally falling well within +/-15% of the experimental temperature measurements. The 300mm (H/8) grid models made much poorer predictions and it was shown that the zone model, although vastly limited in the data it provided was more reliable.