Fire Investigation Using Computer Modelling - Coursework Example

Fire Investigation Using Computer Modelling Name Grade course: Tutor’s Name: Date: Outline I. Introduction II. Applications A. The Spread of Heat and Smoke B. Fire and Explosion Growth C. Presence of Toxic Gases and Other Chemicals D. Determination of Time E. Measurements III. Limitations A. Negligence of Other Important Variables B. Lack of Reality in the Assumptions C. Inaccuracy of Numerical Methods D. Direct Mistakes in Software E. Mistakes in Hardware F. Mistakes in Application IV. Conclusion V. Reference List Introduction The advent of computer modelling has taken the practice of fire and explosion investigation to another level. The invention of state-of-the-art equipment and strategies has gone a long way in improving the effectiveness and accuracy of virtually all fire and explosion investigations. The use of computer modelling in these activities has seen a major breakthrough in this field. One of these achievements is the determination of the exact causes of fire breakouts and explosions just minutes after they have been extinguished. Such significant steps in this sector have also contributed to a substantial decline in the number of intentional arsonists. Currently, a majority of fires occurring across the globe are accidental in nature, thanks to the use of computer modelling in the investigations. However, as much as the use of computer modelling in fire and explosive investigations has a good number of applications, it also has its own limitations. This essay will look at the potential applications and limitations of computer modelling to fire and explosion investigations. APPLICATIONS The Spread of Heat and Smoke Computerized fire models have indeed played a significant role in fire and explosive investigations. This is because they have a wide range of applications in various aspects of the investigations. The applications mainly centre on determining the history of the fire and the explosion. First and foremost, these computerized fire models can be used to predict the spread of heat and smoke in any building in the event of a fire or an explosion. The models are in a position to predetermine the direction of heat and smoke in a building of any design. Examples of computerized fire models that are capable of predicting the direction of heat and smoke in a building in the case of a fire or explosion are the Computational Fluid Dynamics (CFD) models (Drysdale, 1999). This type of models work by solving certain fundamental equations associated with fire. The solved equations result into a description and insight into the fluid flow and heat transfer phenomena of the fire. The determination of these two properties is the key to determining the direction of heat and smoke movement in a building in the event of a fire or an explosion. The prediction of the movement of heat and smoke in a building on fire can help in investigating the actual cause of the fire and explosion. By knowing the direction of movement of the smoke and heat, the investigators will be able to determine its direction of origin and hence the point from where it started. The knowledge of this place will in turn help the investigators to establish the real cause of the fire or explosion. Therefore, computerised fire models are crucial because they give hints that enable investigators to arrive at the exact cause of a fire breakout and explosion. The CFD models have recently become popular because they can be coupled with the modern performance-based codes to ensure an ambience of effective fire safety engineering (Babrauskas, 1995). Fire and Explosion Growth Secondly, computerised fire models can be used to determine the growth of a fire and explosion. This growth refers to the spread or expansion of the fire from its place of ignition. The determination of this growth is significant because it can also lead to the determination of the ignition point and thus the cause of the fire and explosion. This can be done by calculating the velocity of the fire or explosion as it grows and spreads. The velocity of the fire or explosion is at its highest at the point of ignition. This is because the combustibles are whole at this instance. The velocity of the fire therefore reduces with the growth of the fire because the combustibles are perpetually consumed by the fire as it grows. The use of computerised fire models helps in determining the velocity of the fire and subsequently the ignition point of the fire and explosion. Presence of Toxic Gases and Other Chemicals Furthermore, computerised fire models can be used to determine the production of certain types of toxic gases and a variety of chemicals during a fire and an explosion. The gases or chemicals tested by the models are specific to certain types of fires and explosions. The presence of the said toxic gases and chemicals in a fire or explosion can therefore help the investigators to determine the type of fire and explosion and whether it was accidental in nature or whether it was orchestrated by someone (Tuovinen, Holmstedt and Bengtson, 1996). For instance, the presence of chemicals or toxic gases that were not previously at the fire or explosion scene can point to the fact that the fire or explosion was intentionally caused by someone. The absence of the chemicals or gases may be a harbinger that the explosion or fire was the result of an intrinsic accident. The determination of the chemical and gaseous components of a fire or an explosion also be used to determine the motive of the same in cases where it was intentionally caused. The discovery of fatal toxic gases or highly explosive elements within the fire or explosion will indicate that its intention was to cause grave loss of property or even loss of lives. The divulgence of these motives will definitely help in subsequent crime investigations that may be geared at finding out the perpetrators of the explosion or the arsonists (Decker and Ottley, 2009). Determination of Time In addition to that, computerised fire models can be used to determine the exact time that the fire or explosion was caused (Icove and DeHaan, 2004). This can be done by linking the models to automated sprinklers or detectors. The models can then keep a record of the exact time at which the sprinklers or detectors sprang into action. The knowledge of this time can then be used to carry out investigations about the people who may be involved in the fire or explosion incidence. For instance, the investigators can seek to question the people who were around the scene of the fire or explosion at the time of the occurrence of the same. The investigators can also trace the registration numbers of vehicles which were around the scene at the time of the outbreak but were driven off and were not burnt down. Such an investigation will enable the investigators to trace the arsonists or the people behind the explosion. This cannot be made possible without the application of computer modelling in this sector. Measurements Lastly, computerised fire models can be used to measure heat fluxes of fires and explosions, flow rates of fluids involved and the surface and gas temperatures. The determination of these measurements is what gives way to the establishment of the general overall conclusions. The individual values for each measurement named above may be part of a fundamental equation that is crucial in the fire or explosion investigation. The use of computer modelling to find them is therefore a very important step in the course of the investigation. LIMITATIONS Negligence of Other Important Variables The use of computer modelling in fire and explosion investigations also has a number of limitations. The first limitation is that the computerized fire models do not take into account some of the most significant aspects of a fire or explosion. These aspects include the possibility of the ignition of objects using small flames, the ability of fire to spread on surfaces and the heat release rate of the resulting flame. Of these three neglected aspects, the heat release rate is the most significant of them all. In fact, it is often regarded as the most significant variable in the description of a fire or explosion (Babrauskas and Grayson, 1992 Instead of determining the heat release rate of each individual fire or explosion incidence, the models normally work on previously documented heat release rates of similar fires or explosions. The lack of a heat release rate that is measured directly from the flame caused by a fire or an explosion is likely to lead to errors in the investigation of the same. For instance, the inputting of a higher heat release rate than the actual one will result in exaggerated results that will hamstring an effective investigation. In the same manner, the negligence of the capability of fire to spread over a surface and the ignitability of combustibles from small flames also leads to exaggerated results. The inclusion of these two variables increases the area under investigation and thus the heat rate. This leads to more accurate results as opposed to when they are left out. Therefore, the failure of computerized fire models to compute the three variables is a limitation on their usage in fire and explosion investigations. Lack of Reality in the Assumptions Secondly, the use of computerised modelling in fire and explosion investigations lacks a reality in the suppositions made. The conceptual and numerical assumptions that investigators are obliged to posit are not realistic. This is because they are rough estimations of the real fire and explosion cases. These assumptions give room for multiple errors. The probability of the models producing accurate results while working under such false surmises is minimal. The conjectures made rule out the possibility of arriving at an accurate conclusion at the end of the investigation. Therefore, the assumptions made during the fire and explosion investigations in order to set the stage for the operation of computerised fire models are a major limitation to their effectiveness. Inaccuracy of Numerical Methods Moreover, computerised fire models use numerical methods to carry out calculations. These methods are disadvantageous because the use of different methods to compute the same problem gives different answers (Beard, 1992). The different answers point to the high level of inaccuracy of the models. Furthermore, the numerical methods are marginalised and do not take into consideration other factors that affect the values used. The numerical methods do not therefore lead to a general, theoretical solution that extensively addresses each and every issue of the problem. This is also a significant limitation of the use of computer modelling in fire and explosion investigations. Direct Mistakes in Software Furthermore, direct mistakes in the software of computerised fire models may cause serious errors in the computations inputted in them. The mistakes may also result where the software is not an accurate paradigm of the model intended to be used. The end result would be totally wrong conclusions that would be useless in aiding with the fire and explosion investigations. A mistake in the software may also be caused when its physical system is subjected to a condition that it is not used to. The change in the conditions around the software may in turn hamper the effectiveness of the software. Software errors are inevitable to any computerised fire model. The errors result from minor flaws that may be committed during their manufacture or in the course of the investigation. For instance, it is estimated that a thousand lines of a computer source code may be having around eight errors. The same errors also exist even in the most accurate software. Examples are the safety-critical applications which contain approximately four errors in every a thousand lines of computer source code. Therefore, computerised fire models are not an entirely efficient and effective method of investigating fires and explosions. Mistakes in Hardware In addition to that, flaws in the computer hardware may also be a major shortcoming in the use of computer modelling in fire and explosion investigations. This is because the computer hardware has a direct influence on the working of the software and thus the general outcome of the investigations. There is a possibility that the initial computer hardware may change slightly from its initial design by the original manufacturers. This may happen in the course of repairs or movement from one area to another. The change may translate into an error in the working of the software. Mistakes in Application Lastly, a mistake may be made by an operator of a computerized fire model that will cost the accuracy of the fire and explosion investigation. This mistake may take form in the following three ways. First, the operator may have a misunderstanding of the operations of the model as far as its numerical solution techniques are concerned. In this case, the resulting error will be so large that the results may not be documented. This is because the operator may follow a completely different procedure in computing the fundamental equations. If the results acquired from such a calculation are incorporated in the rest of the investigation, then they are bound to render the whole investigation futile. Secondly, the operator of a computerized fire model may make a mistake due to a misunderstanding of the software’s design. This is normally the case if the person has not spent enough time with the model. The lack of experience with the model may contribute to such mistakes at the expense of the accuracy of the investigation. Therefore, all efforts should be made to ensure that the person operating the models has full and correct understanding of its operations. Lastly, the mistake may occur due to a slip in the course of reading the output or inserting the input into the model. The wrong figures entered into the model may then be used throughout the investigation, yielding into a totally wrong conclusion. Therefore, mistakes may happen while handling computerised fire models. Such mistakes are a major limitation in the use of computer modelling in fire and explosion investigations. Conclusion In conclusion, it can be seen from the above discussion that the use of computer modelling in fire and explosion investigations has many applications. The applications include determining the heat flux, fire growth, time and chemical components of a fire or explosion among others. It can also be observed that the models have limitations that hamper their effectiveness in the fire and explosion investigations. Such limitations include unrealistic assumptions, flaws in the computer software and hardware and lastly, mistakes in the application of the models. Reference List Babrauskas, V., 1996. Fire modeling tools for fire safety engineering: are they good enough? J. Fire Protection Engineering, 8(56), p.87-95. Babrauskas, V. and Grayson, S. J., 1992. Heat release in fires. London: Spon. Beard, A.N., 1992. Limitations of computer models. Fire Safety Journal, 18 (19), p.375-391. Decker, J. and Ottley, B., 2009. Arson law and prosecution. Carolina: Carolina Academic Press. Drysdale, D., 1999. An introduction to fire dynamics. Chichester: John Wiley & Sons. Icove, D., and DeHaan, J., 2004. Forensic fire scene reconstruction. Upper Saddle River: Pearson Education, Inc. Tuovinen, H., Holmstedt, G. & Bengtson, S., 1996. Sensitivity calculations of tunnel fires using CFD. Fire Technology, 32 (2), p.99-119. Read More