A CFD method to predict the generation of toxic gases produced by burning external cladding is presented. The model and its assumption have been validated using BS 8414 experimental data for two cladding systems with different aluminium composite materials (ACM). The predicted temperatures are in good agreement with the measured data and the predicted toxic gas concentrations follow the measured trends. The model is then used to assess tenability conditions in a target flat and the lobby five floors above the fire origin, in which toxic smoke penetrates the flat via a half-open kitchen window. Only the impact of cladding materials is considered. Simulations indicate that if the target flat occupants commence their evacuation shortly after alarm activation, they are likely to be able to pass through the lobby and safely evacuate. However, if they delay their evacuation by 21 min, they are likely to become incapacitated due to inhalation of toxic gases. The PIR contribution to the fractional incapacitating dose (FIN) is approximately half that from ACM PE in the target flat and varies from a third to a half in the target lobby. Furthermore, the HCN contribution to the FIN is minor (less than 5%).

A CFD fire model for Living Walls (LW) is presented in this paper. The combustion of the LW support structure (plastic material) is modelled as an external cladding system within SMARTFIRE. The plants and growing medium of the LW system are represented as two groups of combustible porous materials, which consist of solid particles. The combined model provides a unique capability to simulate fires in external LW systems and is validated using data from a variety of LW fire experiments. The model produced good agreement for the measured HRR in an SBI fire test; comparable burning states and temperature profiles of two large-scale tests; and similar time to fail for a LW structure, without plants or growth media, in a BS 8414 test. It is found that although the simulated HRRs from the burning plants are sensitive to the moisture content, the plant mass, the surface area to volume ratio etc., the total HRR of the investigated LW system is dominated by the burning of the plastic structure. It is suggested that the fire risk posed by the investigated LW system is at least as high as that for a Grenfell type cladding system.

A coupled Wells-Riley and CFD modelling technique utilising a multi-size droplet approach is adopted to investigate the transmission route in a COVID-19 infection event. The event occurred in a restaurant in China during 2020 and involved a single suspected index patient and 88 other patrons. Using a multi-size droplet approach involving droplets up to 40 mu m and a back-calculated quanta generation rate, nine secondary infections are predicted in the infection region, as in actual event. Furthermore, in the non-infection region, seating 68 susceptibles, an additional 1.7 infections are predicted. This compares with 23.3 infections when using the aerosol modelling approach (1 mu m droplets). It is also estimated, using tracer gas data from an experiment conducted in this restaurant and simulation data using a small droplet model (5 mu m), both reported in the literature, that there would be 22.0 and 6.1 infections respectively, within the non-infection region. Thus, from these studies, only the multi-size droplet model, with droplets up to 40 mu m can produce a reasonable estimation of the number of secondary infections. This suggests that the transmission of SARS-CoV-2 in this event is dominated by larger droplets, not aerosols or small droplets. The study also suggests that for this event, high ventilation rates alone are not an appropriate mitigation. This research challenges the findings of other researchers that infections in this event were due to small droplets and poor ventilation. Furthermore, table partitions and restricting dining duration are demonstrated to mitigate infection risk, reducing secondary infections by over 50 %.

The COVID-19 pandemic demonstrated a profound inability of pre-pandemic passenger ship policies implemented by both ship operators and governmental authorities to detect and address newly emerging diseases. The essentiality of maritime transport puts into focus the risk of approach to address known and new emerging airborne infectious diseases that, due to increasing capacity, are likely to occur on passenger ships. In order to enhance the passenger experience, prepare shipping for pandemics like COVID-19, and improve the resilience and safety of the industry, this review critically synthesises existing literature on (1) monitoring ventilation conditions and aerosol dispersion, linking them to airborne transmission risk using airborne aerosols and ventilation performance as input parameters for computational fluid dynamics (CFD) simulations, and (2) modelling airborne disease transmission risk in controlled passenger ship environments. This review analysed 39 studies on aerosol monitoring, thermal comfort, and infection risk modelling on passenger ships (2000-2023). Additionally, 55 papers on CFD modelling of airborne pathogen dispersion were reviewed: 22 included validation, with most focused on built environments and only four specifically addressing ship environments. Two major challenges relate to the complexity and poorly characterised ventilation boundary conditions on passenger ships, and the other is the lack of suitable validation data. For this reason, ship experimental studies are required for CFD model validation. Only a handful of studies were found that have measured aerosol concentrations on board passenger ships. To the best of our knowledge, there have been no studies conducted on aerosol mass or airborne transmission sampling on board passenger ships or other types of vessels. The results of this review have the potential to create synergistic connections between experimental and modelling studies to inform, characterise and improve the development of numerical models that can accurately estimate infection risk on ships for prevention, mitigation and management of outbreaks.

Large passenger ships are characterised as enclosed and crowded indoor spaces with frequent interactions between travellers, providing conditions that facilitate disease transmission. This study aims to provide an indoor ship CO2 dataset for inferring thermal comfort, ventilation and infectious disease transmission risk evaluation. Indoor air quality (IAQ) monitoring was conducted in nine environments (three cabins, buffet, gym, bar, restaurant, pub and theatre), on board a cruise ship voyaging across the UK and EU, with the study conducted in the framework of the EU HEALTHY SAILING project. CO2 concentrations, temperature and relative humidity (RH) were simultaneously monitored to investigate thermal characteristics and effectiveness of ventilation performance. Results show a slightly higher RH of 68.2 ± 5.3 % aboard compared to ASHRAE and ISO recommended targets, with temperature recorded at 22.3 ± 1.4 °C. Generally, good IAQ (<1000 ppm) was measured with CO2 mainly varying between 400 and 1200 ppm. The estimated air change rates (ACH) and ventilation rates (VR) implied sufficient ventilation was provided in most locations, and the theatre (VR: 86 L s−1 person−1) and cabins (VR: >20 L s−1 person−1) were highly over-ventilated. Dining areas including the pub and restaurant recorded high CO2 concentrations (>2000 ppm) potentially due to higher footfall (0.6 person m−2 and 0.4 person m−2) and limited ACH (2.3 h−1 and 0.8 h−1), indicating a potential risk of infection; these areas should be prioritised for improvement. The IAQ and probability of infection indicate there is an opportunity for energy saving by lowering hotel load for the theatre and cabins and achieving the minimum acceptable VR (10 L s−1 person−1) for occupants' comfort and disease control. Our study produced a first-time dataset from a sailing cruise ship's ventilated areas and provided evidence that can inform guidelines about the optimisation of ventilation operations in large passenger ships, contributing to respiratory health, infection control and energy efficiency aboard.

A numerical BS 8414 model has been developed using surface ignition temperature, cone calorimeter data and a heat release rate curve from a wood crib, for simulating cladding fires. The model predicts burning rates of combustible materials, temperature profiles, burn-through of materials, burning locations and activation states of functional intumescent cavity barriers. The model is validated using seven DCLG BS 8414 tests, by correctly reproducing pass/fail results and failure mechanisms; producing comparable fire flames and reasonable agreement of temperature profiles, which are essential to the pass/fail criteria; and producing reasonable burning/burnt locations for the cladding system. The model has also been used to investigate factors affecting fire spread including cavity size, state of fire barriers, reduction of core material mass by for example dripping and the consistency of the HRR behaviour of the wood crib fire source. The limitations of the BS 8414 model are discussed including the uncertainty of surface ignition temperature; the approach to the activation of intumescent cavity barriers; the uncertainties in HRRs of the wood crib fire and the material properties. To improve the repeatability of the BS 8414 test, it is suggested that a gas burner is used rather than a wood crib fire.

Understanding airborne pathogen transmission in cruise ship environments remains a critical challenge due to the confined nature of indoor spaces, high occupancy, and limited access for real-world experimentation. This study addresses the gap in empirical data on particulate matter and CO2 dynamics aboard operational cruise ships, providing a high-resolution dataset that can be used for the validation of Computational Fluid Dynamics (CFD) models and informing infection probability risk assessments. An experimental trial was designed for two mechanically ventilated cruise ship rooms (R01, R02), instrumented at ten locations under eight ventilation scenarios: R01 with 100 % (S1a) and 50 % (S1b) design flow rates; R02 with 100 % (S2a), 50 % (S2b) and 10 % (S2c) design flow rates; R01 with high aerosol rate and 50 % flow rate (S3); and R01 with an air purifier at maximum (S4a, 1300 m3 h-1) and minimum (S4b, 422 m3 h-1) clean air delivery rate (CADR). A live UK-EU cruise hosted the experimental trial. Particulate matter and CO2 concentration, temperature and relative humidity were collected using portable sensors to build a unique dataset to validate subsequent computational modelling of aerosol dispersion, infection probability and transmission prevention, mitigation and management (PMM) approaches in arbitrary passenger ship spaces. As expected, PM and CO2 were markedly reduced under 100 % design flow ventilation compared with 50 %. Maximum PM2.5 reductions were 84 % during background, 29 % in build-up, and 72 % in decay experimental phases. An air purifier further reduced particulate matter, with peak PM reductions of 57 % (PM10), 48 % (PM2.5), and 45 % (PM1). These findings offer practical guidance for optimising air quality management strategies in cruise ships and other high-occupancy spaces, besides providing a crucial high-resolution dataset for validating numerical modelling. Moreover, this study provides valuable insights into mechanically ventilated shipboard airflow behaviour.

External living walls (LWs) have aesthetic and environmental appeal, but these characteristics must not compromise fire safety. A review of legislation indicates there are no specific fire regulations or test standards for LWs in England. Furthermore, the 2013 UK Green wall guidance document (GWGD) contradicts current guidance in Approved Document B (ADB) for certain categories of buildings, yet ADB cites GWGD as “best practice”. We suggest the recommended reaction to fire testing methodology for LW systems (single burning item (SBI) EN13823/ignitability EN ISO11925-2 tests) is inappropriate for assessing their fire performance. Despite some limitations, the BS8414 full-scale test could be used to assess LW installations. While not identified in the GWGD or specifically recommended within ADB as a suitable test method for LWs, it is arguably more appropriate than reduced scale SBI testing, primarily because it accommodates full LW modules with planting, and uses a more appropriate fire size. To reduce testing costs, we propose the use of CFD fire modelling, or a modified SBI test to identify candidate LW products likely to pass BS8414 testing. Given the inherent variable nature of LWs and their associated fire properties, LW maintenance is considered essential for on-going compliance with fire safety requirements.

There is ongoing and rapid advancement in approaches to modelling the fate of exhaled particles in different environments relevant to disease transmission. It is important that models are verified by comparison with each other using a common set of input parameters to ensure that model differences can be interpreted in terms of model physics rather than unspecified differences in model input parameters. In this paper, we define parameters necessary for such benchmarking of models of airborne particles exhaled by humans and transported in the environment during breathing and speaking.

Coupled Wells-Riley (WR) and Computational Fluid Dynamics (CFD) modelling (WR-CFD) facilitates a detailed analysis of COVID-19 infection probability (IP). This approach overcomes issues associated with the WR 'well-mixed' assumption. The WR-CFD model, which makes uses of a scalar approach to simulate quanta dispersal, is applied to Chinese long-distance trains (G-train). Predicted IPs, at multiple locations, are validated using statistically derived (SD) IPs from reported infections on G-trains. This is the first known attempt to validate a coupled WR-CFD approach using reported COVID-19 infections derived from the rail environment. There is reasonable agreement between trends in predicted and SD IPs, with the maximum SD IP being 10.3% while maximum predicted IP was 14.8%. Additionally, predicted locations of highest and lowest IP, agree with those identified in the statistical analysis. Furthermore, the study demonstrates that the distribution of infectious aerosols is non-uniform and dependent on the nature of the ventilation. This suggests that modelling techniques neglecting these differences are inappropriate for assessing mitigation measures such as physical distancing. A range of mitigation strategies were analysed; the most effective being the majority (90%) of passengers correctly wearing high efficiency masks (e.g. N95). Compared to the base case (40% of passengers wearing low efficiency masks) there was a 95% reduction in average IP. Surprisingly, HEPA filtration was only effective for passengers distant from an index patient, having almost no effect for those in close proximity. Finally, as the approach is based on CFD it can be applied to a range of other indoor environments.

The Hackitt Report into the tragic loss of 72 lives in the Grenfell Tower fire, identified failures and poor practices associated with the UK construction industry. To address these failures the report makes several recommendations, including the development of a "golden thread of information" to be embedded throughout the entire building lifecycle enabling the recording and preservation of information. This is to be achieved through Building Information Modelling (BIM). However, to create a "golden thread of information" in BIM from the Fire Safety Engineering (FSE) perspective particularly for the performance-based approach, many significant challenges and limitations must be resolved. These challenges include the fact that no FSE specific information exchange is available in BIM and that the results produced by fire and evacuation modelling tools are not explicitly captured in the BIM Industry Foundation Classes (IFC) Model. Of the FSE tools that support BIM, this is mainly limited to geometry extraction from an IFC file. In this paper, a practical conceptual strategy to pave the way to resolve these problems is proposed. A number of developments by the authors are discussed, forming part of an international collaboration project proposal administered by buildingSMART to enhance the IFC Model from the FSE perspective. Additionally, to evaluate and demonstrate the benefits of two-way data flow between BIM and FSE tools, a prototype system together with a preliminary FSE based analysis database have been developed. The work presented in this paper, provides a practical road map for creating a 'golden thread of information' in BIM for performance-based FSE analysis.

Background: An issue of concern to the travelling public is the possibility of in-flight transmission of COVID-19 during long- and short-haul flights. The aviation industry maintain the probability of contracting the illness is small based on reported cases, modelling and data from aerosol dispersion experiments conducted on-board aircraft. Methods: Using experimentally derived aerosol dispersion data for a B777-200 aircraft and a modified version of the Wells-Riley equation we estimate inflight infection probability for a range of scenarios involving quanta generation rate and face mask efficiency. Quanta generation rates were selected based on COVID-19 events reported in the literature while mask efficiency was determined from the aerosol dispersion experiments. Results: The MID-AFT cabin exhibits the highest infection probability. The calculated maximum individual infection probability (without masks) for a 2-hour flight in this section varies from 4.5% for the 'Mild Scenario' to 60.2% for the 'Severe Scenario' although the corresponding average infection probability varies from 0.1% to 2.5%. For a 12-hour flight, the corresponding maximum individual infection probability varies from 24.1% to 99.6% and the average infection probability varies from 0.8% to 10.8%. If all passengers wear face masks throughout the 12-hour flight, the average infection probability can be reduced by approximately 73%/32% for high/low efficiency masks. If face masks are worn by all passengers except during a one-hour meal service, the average infection probability is increased by 59%/8% compared to the situation where the mask is not removed. Conclusions: This analysis has demonstrated that while there is a significant reduction in aerosol concentration due to the nature of the cabin ventilation and filtration system, this does not necessarily mean that there is a low probability or risk of in-flight infection. However, mask wearing, particularly high-efficiency ones, significantly reduces this risk.

Naval platform survivability is a key enabler to ensure maritime warfighting capability. Therefore, assessment of naval platform recoverability, after a damage event, is critical to assure platform survivability in a warfighting environment. To support such an assessment, an innovative modelling and simulation capability, known as the Naval Damage Incident Recoverability Toolset (NavDIRecT) is being developed. NavDIRecT is being designed as a component-based, open architecture providing the necessary framework to allow analysts to integrate domain models of their choosing. NavDIRecT will facilitate analysis of warfighting and peacetime damage events using a variety of mathematical models, thereby avoiding the limitations of other survivability assessment techniques. Development of NavDIRecT is exemplified by integrating the human movement simulator, maritimeEXODUS, the fire simulation environment, SMARTFIRE, and a three-dimensional naval platform model. NavDIRecT will enable analysis of crew interaction with damage events, thereby allowing acquisition programs and mission planners to examine platform survivability with respect to mission capability requirements. The impetus for NavDIRecT development is for assessment of naval platform survivability and mission success; however, the tools and techniques are equally suitable for use in incident management, training, and analysis of merchant and commercial shipping in accordance with the Safety of Life at Sea (SOLAS).

A new type of train configuration, known as Open Wide Gangway (OWG) is becoming popular, particularly in underground environments. Previous fire modelling analysis demonstrated that the OWG configuration was considered safe as or safer than conventional configurations as it reduced the likelihood of flashover. However, these studies have ignored the impact on evacuation of the spread of fire effluent to non-fire cars. Here we explore the fire safety offered by conventional and OWG configurations using coupled fire and evacuation modelling techniques. Two tunnel train situations are considered: one in which the car side doors are available for evacuation (train in a wide tunnel) and the other in which only the end cab doors are available (train in a narrow tunnel). Two population configurations are considered, fully and half loaded. Two ignition sources are also considered, one representing an accidental fire and the other an arson fire. The analysis demonstrates that while the OWG configuration may produce improved fire performance in the car of fire origin compared to the conventional configuration, if the interaction of the fire effluent with the evacuating passengers is considered, the OWG configuration results in a significantly greater number of casualties in virtually all the scenarios considered. Copyright © 2016 John Wiley & Sons, Ltd.

In this paper the computational fluid dynamics fire-field model SMARTFIRE is used to simulate a full-scale aircraft-cabin fire test conducted within the U.S. Federal Aviation Administration furnished C-133 test facility in order to provide further validation for the software. The experiment involves exposing the interior cabin materials to an external fuel fire, noting the subsequent spread of the external fire to the cabin interior and the onset of flashover, which occurs at approximately 210 s. The computational fluid dynamics fire simulations presented in this study make use of a range of sophisticated sub-models including a flame-spread model, the eddy-dissipation model, a toxicity model, and a multi-ray radiation model. The models' ability to simulate the fire conditions within the aircraft cabin is demonstrated through its ability to 1) reproduce the measured trends in temperatures and heat fluxes at the seat tops, 2) reproduce toxic gases concentrations at locations of interest, 3) provide a reasonable prediction of the time to flashover (220 s), and 4) produce reasonable agreement with the observed fire dynamics. The predicted time to flashover is shown to be sensitive to material properties such as ignition temperature of seat materials and not very sensitive to the cabin panel thickness.

SMARTFIRE is an advanced Computational Fluid Dynamics (CFD) fire simulation environment developed by the Fire Safety Engineering Group (FSEG) at the University of Greenwich. Unlike other CFD software used to simulate fire, SMARTFIRE has been specifically designed and developed as a Fire Simulation Tool to be used by Fire Engineers and is based on more than 20 years of CFD fire modelling experience and research of FSEG. This Document Contains - Section 1: Technical Reference Manual Section 2: SMARTFIRE User Guide Section 3: SMARTFIRE Release Notes

This thesis describes the design and implementation of a novel hybrid field/zone fire model, linking a fire field model to a zone model. This novel concept was implemented using SMARTFIRE (a fire field model produced at the University of Greenwich) and two different zone models (CFAST which is produced by NIST and FSEG-ZONE which has been produced by the author during the course of this work). The intention of the hybrid model is to reduce the amount of computation incurred in using field models to simulate multi-compartment geometries, and it will be implemented to allow users to employ the zone component without having to make further technical considerations, in line with the existing paradigm of the SMARTFIRE suite. In using the hybrid model only the most important or complex parts of the geometry are fully modelled using the field model. Other suitable and less important parts of the geometry are modelled using the zone model. From the field model‘s perspective the zone model is represented as an accurate pressure boundary condition. From the zone model‘s perspective the energy and mass fluxes crossing the interface between the models are seen as point sources. The models are fully coupled and iterate towards a solution ensuring both global conservation along with conservation between the regions of different computational method. By using this approach a significant proportion of the computational cells can be replaced by a relatively simple zone model, saving computational time. The hybrid model can be used in a wide range of situations but will be especially applicable to large geometries, such as hotels, prisons, factories or ships, where the domain size typically proves to be extremely computationally expensive for treatment using a field model. The capability to model such geometries without the associated mesh overheads could eventually permit simulations to be run in ‘faster-real-time’, allowing the spread of fire and effluents to be modelled, along with a close coupling with evacuation software, to provide a tool not just for research objectives, but to allow real time incident management in emergency situations. Initial ‘proof of concept’ work began with the development of one way coupling regimes to demonstrate that a valid link between models could allow communication and conservation of the respective variables. This was extended to a two-way coupling regime using the CFAST zone model and results of this implementation are presented. Fundamental differences between the SMARTFIRE and CFAST models resulted in the development of the FSEG-ZONE model to address several issues; this implementation and numerous results are discussed at length. Finally, several additions were made to the FSEG-ZONE model that are necessary for an accurate consideration of fire simulations. The test cases presented in this thesis show that a good agreement with full- field results can be obtained through use of the hybrid model, while the reduction in computational time realised is approximately equivalent to the percentage of domain cells that are replaced by the zone calculations of the hybrid model.

Blended Wing Body (BWB) aircraft with around 1000 passengers and crew are being proposed by aircraft manufacturers. This type of aircraft configuration is radically different from conventional tube type passenger aircraft and so it is essential to explore issues related to both fire and evacuation for these configurations. Due to both the large size and the unusual nature of the cabin layouts, computer simulation provides the ideal method to explore these issues. In this paper we describe the application of both fire and evacuation simulation to BWB cabin configurations. The validity of the computer evacaution simulations is also explored through full-scale evacuation experiments.