A priori filtered chemical source term modeling for LES of high Karlovitz number premixed flames

The Coherent Flamelet Model (CFM) is applied to symmetric counterflow turbulent premixed flames studied by Kostiuk et al. The flame source term is set proportional to the sum of the mean and turbulent rate of strain while flame quenching is modeled by an additional multiplication factor to the flame source term. The turbulent rate of strain is set proportional to the turbulent intensity to match the correlation for the turbulent burning velocity investigated by Abdel-Gayed et al. The predicted flame position and turbulent flow field coincide well with the experimental observations. The relationship between the Reynolds averaged reaction progress variable and flame density seems to show a wrong trend due to inappropriate modeling of the sink and source term in the transport equation.

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Filtered Reaction Rate Modelling in Moderate and High Karlovitz Number Flames: an a Priori Analysis

Flow Turbulence and Combustion ◽

10.1007/s10494-019-00038-8 ◽

2019 ◽

Vol 103 (3) ◽

pp. 643-665 ◽

Cited By ~ 2

Author(s):

Thommie Nilsson ◽

Rixin Yu ◽

Nguyen Anh Khoa Doan ◽

Ivan Langella ◽

Nedunchezhian Swaminathan ◽

...

Keyword(s):

Reaction Rate ◽

A Priori ◽

A Priori Analysis ◽

High Karlovitz Number

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A Priori Direct Numerical Simulation Modeling of Scalar Dissipation Rate Transport in Head-On Quenching of Turbulent Premixed Flames

Combustion Science and Technology ◽

10.1080/00102202.2016.1195823 ◽

2016 ◽

Vol 188 (9) ◽

pp. 1440-1471 ◽

Cited By ~ 11

Author(s):

Jiawei Lai ◽

Nilanjan Chakraborty

Keyword(s):

Numerical Simulation ◽

Direct Numerical Simulation ◽

Simulation Modeling ◽

Dissipation Rate ◽

A Priori ◽

Premixed Flames ◽

Scalar Dissipation ◽

Scalar Dissipation Rate ◽

Turbulent Premixed Flames ◽

Turbulent Premixed

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Release rate estimation of both long- and short-lived radionuclides for the Fukushima Daiichi nuclear accident based on local-scale observations

10.5194/egusphere-egu2020-233 ◽

2020 ◽

Author(s):

Sheng Fang ◽

Xinpeng Li ◽

Shuhan Zhuang

Keyword(s):

Release Rate ◽

Source Term ◽

A Priori ◽

Regional Scale ◽

Local Scale ◽

Gamma Dose ◽

Nuclear Accident ◽

Dose Rates ◽

Gamma Dose Rates ◽

Fukushima Daiichi

Many efforts have been devoted to estimate the release rate of the radionuclide emission in the Fukushima Daiichi nuclear accident using regional scale observations. Because of the radioactive decay, regional scale observations may not provide information of short-lived radionuclides, which contributes the majority of radiation exposure in the early stage. In this study, the local-scale gamma dose rates data were used to estimate the atmospheric release rates of both long- and short-lived radio nuclides.The proposed method uses reactor physics to obtain an a priori radionuclide composition and a reverse source term estimate as an a priori release rate. A weighted additive model is developed, which uses the local-scale gamma dose rates to handle the conflicts between the two priors and to simultaneously incorporate them into the source inversion. The proposed method is validated against both the local-scale gamma dose rates and the regional concentration measurements of Cs-137. The results prove that the retrieved a posteriori source term combines the advantages of both priors and substantially improves the predictions of the on-site gamma dose rates. Given a detailed priori release rate, this approach also improves the regional predictions of both airborne and deposited Cs-137 concentrations.

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Operational evaluation of volcanic source terms (volcanic ash and SO2) from inverse modelling for aviation

10.5194/egusphere-egu2020-4889 ◽

2020 ◽

Author(s):

Mariëlle Mulder ◽

Delia Arnold ◽

Christian Maurer ◽

Marcus Hirtl

Keyword(s):

Source Term ◽

Dispersion Model ◽

Meteorological Data ◽

A Priori ◽

Radar Data ◽

Particle Dispersion ◽

Volcanic Emissions ◽

Volcanic Source ◽

Computational Resources ◽

Different Sources

An operational framework is developed to provide timely and frequent source term updates for volcanic emissions (ash and SO2). The procedure includes running the Lagrangian particle dispersion model FLEXPART with an initial (a priori) source term, and combining the output with observations (from satellite, ground-based, etc. sources) to obtain an a posteriori source term. This work was part of the EUNADICS-AV (eunadics-av.eu), which is a continuation of the work developed in the VAST project (vast.nilu.no). The aim is to ensuring that at certain time intervals when new observational and meteorological data is available during an event, an updated source term is provided to analysis and forecasting groups. The system is tested with the Grimsv&#246;tn eruption of 2011. Based on a source term sensitivity test, one can find the optimum between a sufficiently detailed source term and computational resources. Because satellite and radar data from different sources is available at different times, the source term is generated with the data that is available the earliest after the eruption started and data that is available later is used for evaluation.

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A nonlinear partial differential system arising in thermoelectricity

European Journal of Applied Mathematics ◽

10.1017/s0956792505006212 ◽

2005 ◽

Vol 16 (6) ◽

pp. 683-712 ◽

Cited By ~ 3

Author(s):

A. BERMÚDEZ ◽

R. MUÑOZ-SOLA ◽

F. PENA

Keyword(s):

Source Term ◽

A Priori Estimates ◽

A Priori ◽

Parabolic Partial Differential Equations ◽

Partial Differential ◽

Existence Of A Solution ◽

Nonlinear Parabolic ◽

Priori Estimates ◽

Partial Differential System ◽

Temperature Equation

In this paper we prove the existence of a solution for a system of nonlinear parabolic partial differential equations arising from thermoelectric modelling of metallurgical electrodes undergoing a phase change. The model consists of an electromagnetic problem for eddy current computation coupled with a Stefan problem for temperature. The proof uses a regularized problem obtained by truncating the source term in temperature equation. Passing to the limit requires fine a priori estimates leading to compactness.

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