This thesis promotes the responsible use of CFD technology through the development of the simulation based design strategy applicable to the design of the tire engineered smoke control ventilation systems. The correct representations of the problem of interest and measures that may be adopted to ensure the accuracy of the simulated solution are two key aspects of this promotion. The development process presents the application of the proposed procedure through three industrial challenges that have subsequently been approved by the relevant fire authorities. The challenges consist of the design of fire engineered systems for residential high rise buildings and covered car parks which in turn demonstrate the robustness of the proposed procedure. The proposed procedure consists of four key stages namely: Qualitative Design Review (QDR); Quantitative Analysis (QA); Assessment; and Fire Services' comments. QDR identifies the ventilation strategy, the potential tire scenario and the appropriate assessment approach applicable to the problem of interest. QA uses the chosen tire analytical approach to evaluate parameters identified in the QDR. The assessment stage is where outputs from the analysis are assessed based on the assessment criteria defined in the QDR. Fire Services' comments are there to account for any additional requirements the fire officer responsible might had have as he/she has the final say on whether the fire engineered system is approved for installation. A review of the current legislative literature i.e. building code, prescriptive and performance based codes is presented. Furthermore, the criteria applicable for the assessment of simulation based design solution are also discussed. The concept of smoke control is discussed in detail which includes an overview of the mechanism of smoke movement and the provisions available to limit smoke spread. A survey of the current Computational Fluid Dynamics (CFD) software packages suitable for the assessment of smoke movement is also included.

Coating flows can be defined as a laminar free surface flows, whereby a liquid layer is applied onto a solid substrate. A typical industrial application consists of co-rotating cylindrical rollers, which are used to apply a liquid coating (paint) onto a moving substrate, and depending on the direction of the rollers, can be configured in either forward or reverse mode. These types of coating solution flows are industrially important applications, and convey viscoelastic aspects due to their polymeric content and unsteady polymeric behaviour. The process often possesses localized regions of high shear and extension rates (narrow nip and wetting-line zones), which may cause instabilities on the coated substrate (ribbing, leveling, striping). These non-Newtonian and viscoelastic studies for industrial reverse roll coating focus on the use of computational techniques to model these types of coating flows, alongside the analysis of the fluid flow behaviour and under varied rheological properties. Two flow problem configurations have been considered, a model benchmark problem of mixed combined-separating flow, and the industrial application of reverse roll coating flow. Predictions and corresponding solutions are reported for viscous, inelastic and complex viscoelastic fluid properties. The numerical formulation adopts a Taylor-Galerkin pressure-correction (TGPC) scheme, using a finite element method for viscous, inelastic flows and a hybrid finite element/finite volume method for their viscoelastic counterparts. The research plan is centered around computational fluid dynamics and rheological studies, with the main target focused on industrial roll-coating operations. From simple theory, Newtonian and non-Newtonian coating flows possess specific, yet disparate characteristics. This may lead to distinct and significant differences in their detailed flow behaviour, and in the stressing levels generated, dependent upon the nature of the flow configuration. The study is segmented into several stages: initially, solution was sought for a benchmark flow problem, where a semi- implicit time stepping finite element procedure was employed to simulate a mixed combined- separating flow. Here, both viscous and viscoplastic material approximations have been introduced. Secondly, the industrial application of reverse roll coating flow was addressed for viscous inelastic coating fluids. This incorporated scenarios of inclusion and not of a dynamic wetting line and consideration of the effects of a rubber elastomer-cover upon the applicator roll. Thirdly, viscoelastic paint coatings were addressed for the industrial reverse roll coating flow. Here, a hybrid finite element/finite volume sub-cell method was utilized, and with inclusion of a dynamic wetting line. Of the various viscoelastic material models available, use has been made of the Phan-Thien Taimer (PTT) network class of models, in both linear and exponential variety, and of the FENE class of models, with FENE-CR and FENE-P versions. This has offered a richness in capacity over variation of rheological properties. The choice of computational methods has been justified and the TGPC algorithm was deemed suitable for problem solution. The methodology tested on combined-separating flow provided high-quality numerical results, which compare favorably against experiments, literature and theory. When applied to the reverse roll coating problem, the TGPC algorithm has been coupled to a time-dependent free-surface update procedure, to determine the dynamic movement of the meniscus and the wetting line. Around the nip-region, the flow problem manifests strong flow features, which have been investigated for a range of rheological properties of varying shear and extensional response. The direct impact these have on localized peak nip-pressures and distributional lift levels has been observed, where several relief mechanisms have been successfully identified (important to optimize process control). The influence of solvent fraction, extensional viscosity and increasing elasticity, up to critical stress states have been analysed in considerable detail. In summary, the success of this work indicates optimal flow process settings and preferential Theological coating properties to employ, with respect to this industrial coating process. As such, it lays the foundation and guide towards achieving a stable and consistent coating application - specifically, as high-speed high-gain production is of current demanded.

Devido à crescente preocupação com as questões ambientais envolvendo as emissões de gases que potencializam o efeito estufa e outros problemas associados aos combustíveis fósseis, o hidrogênio aparece como uma fonte de energia alternativa capaz de promover o desenvolvimento de forma sustentável. A produção de hidrogênio via fermentação anaeróbia é uma das rotas mais atraentes atualmente, envolvendo processos físicos, químicos e biológicos com inúmeras interações entre gases, líquidos e sólidos. No entanto, as pesquisas atuais têm dedicado especial atenção às características químicas e biológicas. Muitos reatores em escala real e de laboratório ainda são dimensionados por correlações empíricas, mas a compreensão dos fenômenos hidrodinâmicos envolvidos na produção de hidrogênio é um precursor necessário para a aplicação em projetos de escala industrial. Para otimizar o desempenho do reator, é essencial compreender a dinâmica das fases em seu interior. Neste contexto, o objetivo deste trabalho é empregar técnicas de fluidodinâmica computacional (CFD) para estudar e otimizar o comportamento fluidodinâmico de um reator anaeróbio sequencial em batelada (ASBR). Para tanto, foi adotada uma modelagem bifásica, tridimensional e turbulenta conduzida com o programa computacional OpenFOAM. Diferentes condições operacionais, configurações geométricas, bem como diferentes modelos, foram avaliados. Os resultados obtidos no estudo das forças interfaciais reforçam a importância e a necessidade de validar as simulações com dados experimentais, devido à grande variação nos resultados obtidos em cada caso simulado. Do ponto de vista das configurações geométricas e operacionais, observa-se que modificações na vazão e no sentido da recirculação, bem como alterações na geometria dos distribuidores afetam significativamente a velocidade de mistura e a energia cinética turbulenta no interior do reator. Estas modificações afetam a transferência de massa, a qual influencia diretamente na cinética das reações e possibilita uma maior produção e hidrogênio. Determinar o comportamento do reator de forma precisa é um precursor para propor alterações que melhorem a sua eficiência. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-02-23T13:55:23Z No. of bitstreams: 1 Dissertacao Guilherme Zanella Maurina.pdf: 2001909 bytes, checksum: f1de7c235fc3a85355a86042b3c96826 (MD5) / Made available in DSpace on 2015-02-23T13:55:23Z (GMT). No. of bitstreams: 1 Dissertacao Guilherme Zanella Maurina.pdf: 2001909 bytes, checksum: f1de7c235fc3a85355a86042b3c96826 (MD5) / PETROBRAS, Brasil / Due to the growing concern with environmental issues involving the emission of gases that enhance the greenhouse effect and other problems associated with fossil fuels, hydrogen arises as an alternative source of energy capable of promoting development on a sustainable manner. Hydrogen production via anaerobic fermentation is currently one of the most attractive routes, involving physical, chemical and biological processes with numerous interactions between gas, liquid and solid. However, current research has devoted special attention to chemical and biological characteristics. Many full-scale and laboratory-scale reactors are still dimensioned using empirical correlations, but the understanding of hydrodynamic phenomena involved in the production of hydrogen is a necessary precursor for the application in industrial scale projects. To optimize the performance of the reactor, it is critical to understand the dynamics of the phases inside. In this context, the aim of this work is to employ computational fluid dynamics (CFD) techniques to study and optimize the fluid dynamic behavior of an anaerobic sequential batch reactor (ASBR). Thus, a two-phase, threedimensional and turbulent modeling was adopted, and simulations were conducted with the computer program OpenFOAM. Different operating conditions, geometric configurations and different models were evaluated. The results obtained in the study of interfacial forces reinforce the importance and the need to validate the simulations with experimental data, due to the large variation in the results obtained in each simulated case. Concerning geometric and operational settings, it was observed that changes in flow direction and recirculation, as well as changes in the geometry of distributors, affect significantly the velocity and the turbulent kinetic energy inside the reactor. These changes affect the mass transfer, which directly influences the reaction kinetics and enables greater production of hydrogen. The accurate establishment of the reactor behavior is a precur or to propose changes in order to improve its efficiency.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017. / A framework for optimising a tactical solid rocket motor nozzle is established and investigated within the ANSYS Workbench environment. Simulated results are validated against thrust measurements from the static bench firing of a full-scale rocket. Grid independence is checked and achieved using inflation based meshing. A rocket nozzle contour is parametrized using multiple control points along a spline contour. The design of experiments table is populated by a central composite design method and the resulting response surfaces are used to find a thrust optimised rocket nozzle geometry. CFD results are based on Favre-mass averaged Navier-Stokes equations with turbulence closure implemented with the Menter SST model. Two optimisation algorithms (Shifted Hammersley Sampling and Nonlinear Programming by Quadratic Lagrangian) are used to establish viable candidates for maximum thrust. Comparisons are made with a circular arc, Rao parabolic approximation and conical nozzle geometries including the CFD simulation there-off. The effect of nozzle length on thrust is simulated and optimised within the framework. Results generally show increased thrust as well as demonstrating the framework's potential for further investigations into nozzle geometry optimisation and off-design point characterisation.

Devido à crescente preocupação com as questões ambientais envolvendo as emissões de gases que potencializam o efeito estufa e outros problemas associados aos combustíveis fósseis, o hidrogênio aparece como uma fonte de energia alternativa capaz de promover o desenvolvimento de forma sustentável. A produção de hidrogênio via fermentação anaeróbia é uma das rotas mais atraentes atualmente, envolvendo processos físicos, químicos e biológicos com inúmeras interações entre gases, líquidos e sólidos. No entanto, as pesquisas atuais têm dedicado especial atenção às características químicas e biológicas. Muitos reatores em escala real e de laboratório ainda são dimensionados por correlações empíricas, mas a compreensão dos fenômenos hidrodinâmicos envolvidos na produção de hidrogênio é um precursor necessário para a aplicação em projetos de escala industrial. Para otimizar o desempenho do reator, é essencial compreender a dinâmica das fases em seu interior. Neste contexto, o objetivo deste trabalho é empregar técnicas de fluidodinâmica computacional (CFD) para estudar e otimizar o comportamento fluidodinâmico de um reator anaeróbio sequencial em batelada (ASBR). Para tanto, foi adotada uma modelagem bifásica, tridimensional e turbulenta conduzida com o programa computacional OpenFOAM. Diferentes condições operacionais, configurações geométricas, bem como diferentes modelos, foram avaliados. Os resultados obtidos no estudo das forças interfaciais reforçam a importância e a necessidade de validar as simulações com dados experimentais, devido à grande variação nos resultados obtidos em cada caso simulado. Do ponto de vista das configurações geométricas e operacionais, observa-se que modificações na vazão e no sentido da recirculação, bem como alterações na geometria dos distribuidores afetam significativamente a velocidade de mistura e a energia cinética turbulenta no interior do reator. Estas modificações afetam a transferência de massa, a qual influencia diretamente na cinética das reações e possibilita uma maior produção e hidrogênio. Determinar o comportamento do reator de forma precisa é um precursor para propor alterações que melhorem a sua eficiência. / PETROBRAS, Brasil / Due to the growing concern with environmental issues involving the emission of gases that enhance the greenhouse effect and other problems associated with fossil fuels, hydrogen arises as an alternative source of energy capable of promoting development on a sustainable manner. Hydrogen production via anaerobic fermentation is currently one of the most attractive routes, involving physical, chemical and biological processes with numerous interactions between gas, liquid and solid. However, current research has devoted special attention to chemical and biological characteristics. Many full-scale and laboratory-scale reactors are still dimensioned using empirical correlations, but the understanding of hydrodynamic phenomena involved in the production of hydrogen is a necessary precursor for the application in industrial scale projects. To optimize the performance of the reactor, it is critical to understand the dynamics of the phases inside. In this context, the aim of this work is to employ computational fluid dynamics (CFD) techniques to study and optimize the fluid dynamic behavior of an anaerobic sequential batch reactor (ASBR). Thus, a two-phase, threedimensional and turbulent modeling was adopted, and simulations were conducted with the computer program OpenFOAM. Different operating conditions, geometric configurations and different models were evaluated. The results obtained in the study of interfacial forces reinforce the importance and the need to validate the simulations with experimental data, due to the large variation in the results obtained in each simulated case. Concerning geometric and operational settings, it was observed that changes in flow direction and recirculation, as well as changes in the geometry of distributors, affect significantly the velocity and the turbulent kinetic energy inside the reactor. These changes affect the mass transfer, which directly influences the reaction kinetics and enables greater production of hydrogen. The accurate establishment of the reactor behavior is a precur or to propose changes in order to improve its efficiency.

Orientador: José Roberto Nunhez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T07:13:04Z (GMT). No. of bitstreams: 1 Olino_AnaLeticiaMonteiro_M.pdf: 2635476 bytes, checksum: 1044b4e4ad54faed575660cb81c06763 (MD5) Previous issue date: 2010 / Resumo: Um impelidor ideal para suspensões deve prover a suspensão completa ou homogeneização utilizando o mínimo de energia. O fluxo em um tanque agitado depende da geometria do impelidor, do diâmetro e da localização deste, do diâmetro e do fundo do tanque e da geometria de internos. A Fluidodinâmica Computacional (CFD) é uma ferramenta poderosa para predizer fluxos tridimensionais e distribuição de concentração de sólidos produzidos por impelidores de qualquer configuração geométrica. Este estudo pretende aumentar a capacidade de bombeamento de um impelidor de bombeamento axial, chamado KPC, enquanto mantém o baixo consumo de potência. Para avaliar a capacidade de bombeamento do KPC, diferentes ângulos entre a raiz e a ponta das pás foram estudados. O ângulo da raiz foi mantido em 45º, enquanto o ângulo da ponta da pá foi modificado, resultando em diferentes pás. As simulações em CFD foram feitas com água e com água e areia. O modelo de turbulência utilizado foi o Shear Stress Transport (SST) e foi utilizada a técnica de simulação Sliding Grid. O modelo escolhido para as simulações foi validado experimentalmente. O descolamento da camada limite na ponta das pás dos impelidores foi visualizado, e o objetivo principal do trabalho, encontrar o impelidor KPC otimizado, foi atingido. Este impelidor possui 45º na raiz da pá e 10º na ponta da pá. O impelidor otimizado confirmou seu melhor desempenho quando comparado ao impelidor inicial na simulação de uma suspensão de areia e água / Abstract: An ideal impeller for solid suspension should provide complete suspension or homogenization consuming a minimum of energy. The flow in a stirred tank depends on impeller design, diameter and the location of impellers, vessel diameter, bottom design and internals. Computational Fluid Dynamics (CFD) is a powerful tool to predict the three dimensional flow and solids concentration distribution produced by different impellers of any geometric configuration. This study aims to improve the pumping of an axial pumping impeller, named KPC, while maintaining low power consumption. In order to evaluate the pumping capacity of the KPC impeller, differents angles between the root and the tip of the blades have been studied. The angle at the root was maintained at 45º, and the angle at the blade tip has been modified, resulting in different blades. CFD simulations were performed for water and for water and sand. The model used the Shear Stress Transport (SST) turbulence model and the Sliding Grid simulation strategy. The model was validated against experimental data. The impelller blade flow separation was visualized, and the main objective of the work, which was to find the optimized KPC impeller, was reached. This impeller possess 45º in the blade root and 10º in the tip of the blade. The optimized impeller confirmed its better performance when compared to the initial impeller in a simulation of a suspension of sand and water / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Submitted by Marcele Costal de Castro (costalcastro@gmail.com) on 2017-10-04T17:13:38Z No. of bitstreams: 1 PAULO AUGUSTO BERQUÓ DE SAMPAIO D.pdf: 6576641 bytes, checksum: 71355f6eedcf668b2236d4c10f1a2551 (MD5) / Made available in DSpace on 2017-10-04T17:13:38Z (GMT). No. of bitstreams: 1 PAULO AUGUSTO BERQUÓ DE SAMPAIO D.pdf: 6576641 bytes, checksum: 71355f6eedcf668b2236d4c10f1a2551 (MD5) Previous issue date: 1991-09 / The basic difficulties associated with the numerical solution of the incompressible Navier-Stokes equations in primitive variables are identified and analysed. These difficulties, namely the lack of self-adjointness of the flow equations and the requirement of choosing compatible interpolations for velocity and pressure, are addressed with the development of consistent Petrov-Galerkin formulations. In particular, the solution of incompressible viscous flow problems using simple equal order interpolation for all variables becomes possible .

Orientador: Sávio Souza Venâncio Vianna / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-26T06:41:15Z (GMT). No. of bitstreams: 1 Matos_RenataPintodaSilva_M.pdf: 3725147 bytes, checksum: 25df8714a04182bf23945239ed396ad9 (MD5) Previous issue date: 2014 / Resumo: A máxima sobrepressão de uma explosão de gás é um dos principais parâmetros estimados em uma Análise de Consequências. Muitas vezes é necessário fazer estimativas iniciais do seu valor, principalmente na fase conceitual de projeto. Portanto um modelo para estimativa da máxima sobrepressão gerada em uma explosão de gás que é de fácil implementação e que possui uma abordagem teórica foi desenvolvido. Ele foi implementado no software de planilhas eletrônicas Microsoft Excel e apresenta tempo de resposta curto. O modelo desenvolvido é baseado no conceito flamelet como apresentado por BML (Bray, Moss e Libby). Ele considera o efeito de obstáculos na aceleração da chama em uma explosão dentro de uma câmara em larga escala com vent. A modelagem da energia cinética turbulenta e da sua taxa de dissipação é baseada em fluidodinâmica computacional (CFD). Simulações numéricas foram conduzidas no FLACS (Flame Acceleration Simulator). O desempenho do modelo foi avaliado em três diferentes conjuntos de dados experimentais de explosões de gás em larga escala dentro de câmaras parcialmente confinadas e obstruídas similares a um módulo offshore: os experimentos da British Gas, Shell e DNV. O modelo foi capaz de representar o aumento da área da chama devido à turbulência causada pela presença de obstáculos para os três experimentos em questão. Espera-se que o modelo seja capaz de representar o mesmo comportamento em geometrias similares à da British Gas sem o ajuste de constantes. Comparações com modelos existentes que não são de CFD mostraram um desempenho muito promissor e uma boa concordância com dados experimentais foi observada / Abstract: The maximum overpressure of gas explosion is one of the main parameters estimated in the Consequence Analysis. Quite often it is necessary to make some initial estimative of its value, particularly in the conceptual design phase. Therefore a model to estimate the maximum overpressure of gas explosion that is easy to implement and have a theoretical approach has been developed. It has been implemented in the Microsoft Excel spreadsheet and it presents a short response time. The developed model is based on the flamelet concept as put forward by BML (Bray, Moss and Libby). It takes into account the effect of obstacles on the flame acceleration in the explosion inside a large scale chamber with vent. The modelling of the turbulent kinetic energy as well as the rate of dissipation of turbulent kinetic energy is based on computational fluid dynamics (CFD). Numerical simulations were conducted in FLACS (Flame Acceleration Simulator). The performance of the model has been verified for three different sets of experimental data from large scale gas explosions inside partially confined and obstructed chambers which are similar to an offshore module: the experiments from British Gas, Shell and DNV. The model was capable of representing the increase of the flame area due to the turbulent field ahead of the flame caused by the presence of obstacles for the three experiments. It is expected that the model is able to represent the same behaviour in geometries similar to the British Gas without the constant adjustment. Comparisons with existing non CFD models have shown a very promising performance and good agreement with experimental data was observed / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestra em Engenharia Química

The study of magnetohydrodynamics unifies the fields of fluid mechanics and electrodynamics to describe the interactions between magnetic fields and electrically conducting fluids. Flows described by magnetohydrodynamics form a significant aspect in a wide range of engineering applications, from the liquid metal blankets designed to surround and remove heat from nuclear fusion reactors, to the delivery and guidance of nanoparticles in magnetic targeted drug delivery. The ability to optimize these, and other, processes is increasingly reliant on the accuracy and stability of the numerical models used to predict such flows. This thesis addresses this by providing a detailed assessment on the performance of two electromagnetically extended Reynolds-averaged Navier-Stokes models through computations of a number of electromagnetically influenced simple channel and Rayleigh-Bènard convective flows. The models tested were the low-Re k-ε linear eddy-viscosity model of Launder and Sharma (1974), with electromagnetic modifications as proposed by Kenjereš and Hanjalić (2000), and the low-Re stress-transport model of Hanjalić and Jakirlić (1993), with electromagnetic modifications as proposed by Kenjereš and Hanjalić (2004). First, a one-dimensional fully-developed turbulent channel flow was considered over a range of Reynolds and Hartmann numbers with a magnetic field applied in both wall-normal and streamwise directions. Results showed that contributions from the electromagnetic modifications were modest and, whilst both models inherently captured some of the reduction in mean strain that a wall-normal field imposed, results from the stress-transport model were consistently superior for both magnetic field directions. Then, three-dimensional time-dependent Rayleigh-Bènard convection was considered for two different Prandtl numbers, two different magnetic field directions and over a range of Hartmann numbers. Results revealed that, at sufficiently high magnetic field strengths, a dramatic reorganization of the flow structure is predicted to occur. The vertical magnetic field led to a larger number of thinner, more cylindrical plumes whilst the horizontal magnetic field caused a striking realignment of the roll cells' axes with the magnetic field lines. This was in agreement with both existing numerical simulations and physical intuition. The superior performance of the modified stress-transport model in both flows was attributed to both its ability to provide better representation of stress generation and other processes, and its ability to accommodate the electromagnetic modifications in a more natural, and exact, fashion. The results demonstrate the capabilities of the stress-transport approach in modelling MHD flows that are relevant to industry and offer potential for those wishing to control flow structure or levels of turbulence without recourse to mechanical means.

Combustion research currently aims to reduce emissions, whilst improving the fuel economy. Burning fuel in excess of air, or lean-burn combustion, is a promising alternative to conventional combustion, and can achieve these requirements simultaneously. However, lean-burn combustion poses new challenges, especially for internal combustion (IC) engines. Therefore, models used to predict such combustion have to be reliable, accurate and robust. In this work, the flamelet approach in the Reynolds-Averaged Navier- Stokes framework, is used to simulate flames relevant to spark-ignition IC engines. A central quantity in the current modelling approach is the scalar dissipation rate, which represents coupling between reaction and diffusion, as well as the flame front dynamics. In the first part of this thesis, the predictive ability of two reaction rate closures, viz. strained and unstrained flamelet models, are assessed through a series of experimental test cases. These cases are: spherically propagating methane- and hydrogen-air flames and combustion in a closed vessel. In addition to these models, simpler algebraic closures are also used for comparison. It is shown that the strained flamelet model can predict unconfined, spherically propagating methane-air flames reasonably well. By comparing spherical flame results with planar flames, under identical thermochemical and turbulence conditions, it is shown that the turbulent flame speed of spherical flames are 10 to 20% higher than that of planar flames, whilst the mean reaction rates are less influenced by the flame geometry. Growth of the flame brush thickness in unsteady spherical flames have been attributed to turbulent diffusion in past studies. However, the present analyses revealed that the dominant cause for this increase is the heat-release induced convective effects, which is a novel observation. Unlike methane-air flames, hydrogen-air flames have non-unity Lewis numbers. Hence, a novel two degrees of freedom approach, using two progress variables, is used to describe the thermochemistry of hydrogen-air flames. Again, it is shown that the strained flamelet model is able to predict the experimental flame growth for stoichiometric hydrogen-air flames. However, none of the models used in this work were able to predict lean hydrogen-air flames. This is because these flames are thermo-diffusively unstable and the current approach is inadequate to represent them. When combustion takes place inside a closed vessel, the compression of the end gases by the propagating flame causes the pressure to rise. This is more representative of real IC engines, where intermittent combustion takes place. The combustion models are implemented in a commercial computational fluid dynamics (CFD) code, STAR-CD, and it is shown that both strained and unstrained flamelet models are able to predict the experimental pressure rise in a closed vessel. In the final part of this work, a spark-ignition engine is simulated in STAR-CD using the flamelet model verified for simpler geometries. It is shown that this model, together with a skeletal mechanism for iso-octane, compares reasonably well with experimental cylinder pressure rise. Results obtained from this model are compared with two models available in STAR- CD. These models require some level of tuning to match the experiments, whereas the modelling approach used in this work does not involve any tunable parameters.