Abstract:SUMMARYThis paper illustrates the use of simplified P N approximations as a tools of achieving verification of codes and simulations of radiative transfer in combustion systems. The main advantage of considering these models is the fact that the integro-differential equation for radiative transfer can be replaced by a set of differential equations which are independent of angle variable, compatible to the partial differential equations of flow and combustion, and easy to solve using standard numerical discreti… Show more
“…The simplified P N approximations have also been studied in [9,13,15] for glass manufacturing, in [16] for crystal growth, in [17][18][19] for gas turbines, and in [20] for low Mach number flows. Recently, validation of the simplified P N approximations with experimental measurements has been carried out in [21] for a three-dimensional diffusion flame. In the current work, we extend the SP 1 approximations to the radiation-convection flow past a cylinder.…”
Section: The Simplified P 1 Approximationmentioning
We propose a finite element method for solving combined convection and radiation in laminar flow past a circular cylinder. The flow problem is described by the thermal incompressible Navier-Stokes equations subject to a Boussinesq approach. To incorporate radiation into the model we consider a simplified P 1 approximation of the radiative transfer equation. The numerical solution of the governing equations is performed by a Galerkin-characteristic method using finite element discretization. The method is accurate and stable for a wide range of optical scales and Reynolds numbers. In addition, the characteristic treatment in the method eliminates most of the numerical difficulties that usually appear in the Eulerian-based methods for convection-dominated problems. Numerical results are presented and comparisons between simulations with and without radiation are also illustrated.
“…The simplified P N approximations have also been studied in [9,13,15] for glass manufacturing, in [16] for crystal growth, in [17][18][19] for gas turbines, and in [20] for low Mach number flows. Recently, validation of the simplified P N approximations with experimental measurements has been carried out in [21] for a three-dimensional diffusion flame. In the current work, we extend the SP 1 approximations to the radiation-convection flow past a cylinder.…”
Section: The Simplified P 1 Approximationmentioning
We propose a finite element method for solving combined convection and radiation in laminar flow past a circular cylinder. The flow problem is described by the thermal incompressible Navier-Stokes equations subject to a Boussinesq approach. To incorporate radiation into the model we consider a simplified P 1 approximation of the radiative transfer equation. The numerical solution of the governing equations is performed by a Galerkin-characteristic method using finite element discretization. The method is accurate and stable for a wide range of optical scales and Reynolds numbers. In addition, the characteristic treatment in the method eliminates most of the numerical difficulties that usually appear in the Eulerian-based methods for convection-dominated problems. Numerical results are presented and comparisons between simulations with and without radiation are also illustrated.
“…The relevance of the search for the new algorithms to solve the complex heat transfer systems is determined by practical applications in the production of glass [1] and in the combustion chambers [2]. The system consists of the differential heat transfer equation and integrodifferential equation of radiative transfer.…”
Section: Introduction and Problem Statementmentioning
The problems of the non-stationary complex heat transfer have been considered in the work. An optimization algorithm based on machine learning methods has been proposed. The algorithm uses a neural network trained on a dataset of numerical experiments to predict the value of a chosen quality functional. Dual annealing method has been used to minimize neural network prediction function while varying boundary parameters. The obtained results are verified by comparison with numerical experiments.
“…Originally intended for applications in nuclear engineering, the SP N equations are, indeed, implemented and used for neutron transport problems nowadays [2,6,18,9]. After first theoretical foundations for the SP N method were provided, a wide range of additional applications has been developed mainly in the past decade, e.g., radiative cooling of glass [30,11], radiative transfer in tissue [22], fluorescence tomography [23], design of combustion chambers for gas turbines [35,36], crystal growth of semitransparent materials [1], and photon and electron radiotherapy [24].…”
The steady-state simplified P N (SP N ) approximations to the linear Boltzmann equation have been proven to be asymptotically higher-order corrections to the diffusion equation in certain physical systems. In this paper, we present an asymptotic analysis for the time-dependent simplified P N equations up to N = 3. Additionally, SP N equations of arbitrary order are derived in an ad hoc way. The resulting SP N equations are hyperbolic and differ from those investigated in a previous work by some of the authors. In two space dimensions, numerical calculations for the P N and SP N equations are performed. We simulate neutron distributions of a moving rod and present results for a benchmark problem, known as the checkerboard problem. The SP N equations are demonstrated to yield significantly more accurate results than diffusion approximations. In addition, for sufficiently low values of N , they are shown to be more efficient than P N models of comparable cost.
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