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Title: Determining transport coefficients for a microscopic simulation of a hadron gas

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1342613
Grant/Contract Number:
SC0008132; FG02-03ER41259
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 95; Journal Issue: 2; Related Information: CHORUS Timestamp: 2017-02-06 11:59:18; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Pratt, Scott, Baez, Alexander, and Kim, Jane. Determining transport coefficients for a microscopic simulation of a hadron gas. United States: N. p., 2017. Web. doi:10.1103/PhysRevC.95.024901.
Pratt, Scott, Baez, Alexander, & Kim, Jane. Determining transport coefficients for a microscopic simulation of a hadron gas. United States. doi:10.1103/PhysRevC.95.024901.
Pratt, Scott, Baez, Alexander, and Kim, Jane. Fri . "Determining transport coefficients for a microscopic simulation of a hadron gas". United States. doi:10.1103/PhysRevC.95.024901.
@article{osti_1342613,
title = {Determining transport coefficients for a microscopic simulation of a hadron gas},
author = {Pratt, Scott and Baez, Alexander and Kim, Jane},
abstractNote = {},
doi = {10.1103/PhysRevC.95.024901},
journal = {Physical Review C},
number = 2,
volume = 95,
place = {United States},
year = {Fri Feb 03 00:00:00 EST 2017},
month = {Fri Feb 03 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevC.95.024901

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

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  • The Bird algorithm is a computationally efficient method for simulating dilute gas flows. However, due to the relatively large transport coefficients at low densities, high Rayleigh or Reynolds numbers are difficult to achieve by this technique. We present a modified version of the Bird algorithm in which the relaxation processes are enhanced and the transport coefficients reduced, while preserving the correct equilibrium and nonequilibrium fluid properties. The present algorithm is found to be two to three orders of magnitude faster than molecular dynamics for simulating complex hydrodynamical flows.
  • The formal expressions for transport coefficients which are obtained in the ensemble theory of irreversible processes are investigated and a method for reducing them to more practical forms is proposed. To this end, a manybody theory is developed which makes use of a perturbation expansion in terms of a scattering matrix or t-matrix, rather than the potential, and is thus immediately applicable to situations in which the interaction potential contains a hard core. A transport coefficient is related to a time integral of a microscopic correlation function whose time dependence is described by the non-Markovian generalized master equation of vanmore » Hove. A simplified derivation of this equation is given and the quantities which appear in it are expressed in terms of the t-matrix. In general the evaluation of a transport coefficient requires that non-Markovian effects be taken into consideration. It is shown that transport coefficients for a system in a quasi-steady state can be determined from the generalized Pauli equation (which is a Markovian equation) which is derived from the generalized master equation. The density dependence of the various quantities which appear are analyzed and the Pauli equation and the expression for the transport coefficient are obtained in the limit of low density. It is demonstrated that in this limit the N-body dependence of the equations can be reduced to a one-body dependence, and in fact, the results are identical to those obtained using the Boltzmann transport equation. These results are obtained without performing coarse-graining or time-smoothing operations or assuming molecular chaos, whereas these are required in the usual derivations of the Boltzmann equation. As an example, the formalism is applied to the thermal conductivity of a dilute non-degenerate quantum gas, and the result obtained agrees with the Boltzmann equation result.« less
  • Contaminant distribution coefficients determined under saturated conditions are often used to model transport under unsaturated conditions. Although the distribution coefficients are assumed to be consistent under different moisture conditions, this is rarely tested. Column and batch adsorption tests were used to determine strontium distribution coefficients in crushed basalt. Column tests were conducted at saturated and unsaturated moisture contents. Batch tests were conducted at several solid/liquid ratios. Preliminary column tests using bromide as a conservative tracer indicated the presence of immobile water in the column and pointed toward the use of a two-region model to determine the Sr distribution coefficients. Usemore » of a single-region model, however, resulted in an average value not significantly different than the average value determined using the two-region model. Moisture content had no significant effect on Sr distribution coefficients determined by applying either model to the column test data. The batch test distribution coefficient determined at the recommended standard solid-liquid ratio was less than the column test values and decreased significantly with increasing solid/liquid ratio. The results indicate that K{sub d}s determined with this method will not accurately reflect Sr transport in unsaturated or saturated basalt.« less