No abstract

Articles you may be interested inComparison of maximum entropy and quadrature-based moment closures for shock transitions prediction in onedimensional gaskinetic theory AIP Conf.Abstract. The performance of a novel maximum-entropy-based 14-moment interpolative closure is examined for multidimensional flows via validation of the closure for several established benchmark problems. Despite its consideration of heat transfer, this 14-moment closure contains closed-form expressions for the closing fluxes, unlike the maximum-entropy models on which it is based. While still retaining singular behaviour in some regions of realizable moment space, the interpolative closure proves to have a large region of hyperbolicity while remaining computationally tractable. Furthermore, the singular nature has been shown to be advantageous for practical simulations. The multi-dimensional cases considered here include Couette flow, heat transfer between infinite parallel plates, subsonic flow past a circular cylinder, and lid-driven cavity flow. The 14-moment predictions are compared to analytical, DSMC, and experimental results as well the results of other closures. For each case, a range of Knudsen numbers are explored in order to assess the validity and accuracy of the closure in different regimes. For Couette flow and heat transfer between flat plates, it is shown that the closure predictions are consistent with the expected analytical solutions in all regimes. In the cases of flow past a circular cylinder and lid-driven cavity flow, the closure is found to give more accurate results than the related lower-order maximum-entropy Gaussian and maximum-entropy-based regularized Gaussian closures. The ability to predict important non-equilibrium phenomena, such as a counter-gradient heat flux, is also established.

The predictive capabilities of a new, 14-moment, maximum-entropy-based, interpolative closure are explored for multi-dimensional non-equilibrium flows with heat transfer. Unlike the maximum-entropy closure on which it is based, the interpolative closure provides closed-form expressions for the closing fluxes. While still presenting singular solutions in regions of realizable moment space, the interpolative closure proves to have a large region of hyperbolicity while remaining tractable. Furthermore, its singular nature is deemed advantageous for practical simulations. An implicit finite-volume procedure is proposed and described for the numerical solution of the 14-moment closure on two-dimensional computational domains, followed by a presentation and discussion of the results of a numerical dispersion analysis. Multi-dimensional applications of the closure are then examined for several canonical flow problems in order to provide an assessment of the capabilities of this novel closure for a range of non-equilibrium flows. The computational performance of the implicit solver is compared to a semi-implicit method. The predictive capabilities of the 14-moment interpolative closure were found to surpass those of the 10-moment Gaussian closure. It was also found to predict interesting non-equilibrium phenomena, such as counter-gradient heat flux. The implicit solver showed improved computational performance compared to the previously studied semi-implicit technique.

No abstract