English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

In this work, we have theoretically analyzed and numerically evaluated theaccuracy of high-order lattice Boltzmann (LB) models for capturingnon-equilibrium effects in rarefied gas flows. In the incompressible limit, theLB equation is proved to be equivalent to the linearized Bhatnagar-Gross-Krook(BGK) equation. Therefore, when the same Gauss-Hermite quadrature is used, LBmethod closely assembles the discrete velocity method (DVM). In addition, theorder of Hermite expansion for the equilibrium distribution function is foundnot to be correlated with the approximation order in terms of the Knudsennumber to the BGK equation, which was previously suggested by\cite{2006JFM...550..413S}. Furthermore, we have numerically evaluated the LBmodels for a standing-shear-wave problem, which is designed specifically forassessing model accuracy by excluding the influence of gas molecule/surfaceinteractions at wall boundaries. The numerical simulation results confirm thatthe high-order terms in the discrete equilibrium distribution function play anegligible role. Meanwhile, appropriate Gauss-Hermite quadrature has the mostsignificant effect on whether LB models can describe the essential flow physicsof rarefied gas accurately. For the same order of the Gauss-Hermite quadrature,the exact abscissae will also modestly influence numerical accuracy. Using thesame Gauss-Hermite quadrature, the numerical results of both LB and DVM methodsare in excellent agreement for flows across a broad range of the Knudsennumbers, which confirms that the LB simulation is similar to the DVM process.Therefore, LB method can offer flexible models suitable for simulatingcontinuum flows at Navier Stokes level and rarefied gas flows at the linearizedBoltzmann equation level.

Accuracy analysis of high-order lattice Boltzmann models for rarefied gas flows