Evaporation Boundary Conditions for the Linear R13 Equations Based on the Onsager Theory

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dc.contributor.author Beckmann, Alexander
dc.contributor.author Rana, Anirudh
dc.contributor.author Torrilhon, Manuel
dc.contributor.author Struchtrup, Henning
dc.date.accessioned 2018-09-07T21:12:21Z
dc.date.available 2018-09-07T21:12:21Z
dc.date.copyright 2018 en_US
dc.date.issued 2018
dc.identifier.uri http://dx.doi.org/10.3390/e20090680
dc.identifier.uri http://hdl.handle.net/1828/10046
dc.description.abstract Due to the failure of the continuum hypothesis for higher Knudsen numbers, rarefied gases and microflows of gases are particularly difficult to model. Macroscopic transport equations compete with particle methods, such as the Direct Simulation Monte Carlo method (DSMC), to find accurate solutions in the rarefied gas regime. Due to growing interest in micro flow applications, such as micro fuel cells, it is important to model and understand evaporation in this flow regime. Here, evaporation boundary conditions for the R13 equations, which are macroscopic transport equations with applicability in the rarefied gas regime, are derived. The new equations utilize Onsager relations, linear relations between thermodynamic fluxes and forces, with constant coefficients, that need to be determined. For this, the boundary conditions are fitted to DSMC data and compared to other R13 boundary conditions from kinetic theory and Navier–Stokes–Fourier (NSF) solutions for two one-dimensional steady-state problems. Overall, the suggested fittings of the new phenomenological boundary conditions show better agreement with DSMC than the alternative kinetic theory evaporation boundary conditions for R13. Furthermore, the new evaporation boundary conditions for R13 are implemented in a code for the numerical solution of complex, two-dimensional geometries and compared to NSF solutions. Different flow patterns between R13 and NSF for higher Knudsen numbers are observed. en_US
dc.description.sponsorship A.F.B. and H.S. are supported by the Natural Sciences and Engineering Research Council (NSERC). A.S.R. thankfully acknowledges the funding from EPSRC Grant EP/N016602/1 in the U.K. and European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska Curie Grant Agreement No. 713548. en_US
dc.language.iso en en_US
dc.publisher Entropy en_US
dc.rights Attribution-NonCommercial-NoDerivs 2.5 Canada *
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/2.5/ca/ *
dc.title Evaporation Boundary Conditions for the Linear R13 Equations Based on the Onsager Theory en_US
dc.type Article en_US
dc.description.scholarlevel Faculty en_US
dc.description.reviewstatus Reviewed en_US

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