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Showing 1 to 16 of 16 for “"Progress variable"”.
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Unsteady flamelet progress variable modeling of reacting diesel jets
… part of this work, an existing unsteady flamelet progress variable (UFPV) model is employed in Reynolds-averaged Navier-Stokes (RANS) simulations and large-eddy simulations (LES) to assess its accuracy. The RANS simulations predict that ignition occurs toward the leading tip of the jet, followed …
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Large eddy simulation of premixed combustion using flamelets
… algebraic expression for the reaction rate of a progress variable and the assumption of fast chemistry, the other based on a database of unstrained flamelets in which reaction rates are stored and parametrised using a progress variable and its SGS variance, and their potentials are shown for a …
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Simulation of partially premixed turbulent flames
… describing mixing and a reaction parameter, progress variable. The laminar flamelet concept is adopted to decouple chemistry and turbulence calculations for high computational efficiency. This modelling framework is validated using two experimental test cases in this study including a …
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Conditional source-term estimation methods for turbulent reacting flows
… extended to include radiation by introducing a variable enthalpy defect to parameterize TGLDM manifolds. The results are compared to the adiabatic computation and the experimental data. The prediction of NO formation is improved, though the predictions of temperature and major products show no …
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Scalar dissipation rate based flamelet modelling of turbulent premixed flames
… are parametrised by scalar dissipation rate of progress variable which is a suitable quantity to describe the flamelet structure since it is governed by convection--diffusion--reaction balance and represents the flame front dynamics. This paramaterisation is new. The mean reaction rate and mean …
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Turbulent partially premixed combustion: DNS analysis and RANS simulation
… rates (SDR) of the mixture fraction ẼZZ, progress variable Ẽcc and their cross dissipation rates (CDR) ẼcZ are identified as important quantities in the modelling of partially premixed flames. Their behaviours in the lifted flame stabilisation region are examined in a unified framework. It …
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Identification, Intervention and Outcomes for Children with Dyslexia
… average intervention period of four years. The progress made in reading/spelling by each child between the baseline and review, constituted the progress variable. Provision data obtained from parents and teachers constituted the provision variable. The progress made by children in three …
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Autonomous Racing and Overtaking for the Voyager Unmanned Ground Vehicle
… by a piecewise linear spline as a function of a progress variable. The dynamic obstacle is represented by its predicted position trajectory as a function of time. The model predictive contouring control problem is formulated and solved using a numerical optimiser. Simulation experiments are …
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Computations of Turbulent Premixed Flames Using Conditional Moment Closure
… rate (CSDR) of the conditioning scalar, the progress variable. In premixed CMC, this term is an important quantity and represents the rate of mixing at small scales of relevance for combustion. The numerical accuracy of the CMC method depends on the accuracy of the CSDR model. In this study, …
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DNS of inhomogeneous reactants premixed combustion
… are characterised by an isosurface of reaction progress variable. The unsteady flames are compared to the steady laminar unstrained reference case. An equivalence ratio dip is observed in all simulations and it can serve as a marker for the premixed flame. The dip is attributed to the …
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Advancing turbulent reacting flow simulations with generalisable machine learning models for sub-grid FDF
… employs the first and second moments of the progress variable and mixture fraction as input features, with the filtered mixture fraction expressed in a logarithmic form to ensure consistency across different combustion regimes. A priori assessments demonstrate that the ANN effectively …
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Arsenic Release from Chlorine Promoted Oxidation of Pyrite in the St. Peter Sandstone Aquifer, Eastern Wisconsin
… released sulfate ion, used here as the reaction progress variable. EPMA maps also reveal complete oxidation of pyrite cements to Fe-oxyhydroxides at 1200 mg/L "free chlorine" and pH 7.0. This behavior does not occur at lower concentrations or higher pH. Arsenic release to solution does not appear …
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A computational and experimental study of spark ignition engine combustion
… reconstruction of the mean combustion progress variable field for three different engine speeds. As the flame approached the combustion chamber walls it was found to decelerate. A relationship between the burning velocity of an unconstrained flame and a flame approaching a wall was …
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CFD Simulation of Combustion Using Automatically Reduced Reaction Mechanisms : A Case for Diesel Engine
… chemistry to be expressed only in terms of a few progress variables. It allows the prediction of intermediate and minor species in order to accurately capture the flame propagation and predict pollutant formation. In current work, using n-heptane as a model Diesel fuel, a one- and two-dimensional …
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Modelling of Spray Combustion with Doubly Conditional Moment Closure
… based on mixture fraction and reaction progress variable permits us to resolve premixed, non-premixed and intermediate combustion modes. In the first part of this thesis, the model development is presented. With its foundation as a statistical model, DCMC does not require any strong …
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Pyrolysis and Flamelet Model for Polymethyl Methacrylate in Solid Fuel Sc(ramjet) Combustors
… were also simulated using the flamelet-progress variable approach in two different oxidizer conditions. All of these simulations showed strong agreement with experimental data and helped to uncover flame holding characteristics of the scramjet cavities and the strong coupling between the …