Properties of the aggregated quasi-hydrodynamic system of equations for a homogeneous gas mixture with a common regularizing velocity

We study a quasi-hydrodynamic system of equations for a homogeneous (with common velocity and temperature) multicomponent gas mixture in the absence of chemical reactions, with a regularizing velocity common for the components. We derive the entropy balance equation with a non-negative entropy production taking into account the diffusion fluxes of the mixture components. In the absence of diffusion fluxes, a system of equations linearized at a constant solution is constructed by a new technique, In the absence of diffusion fluxes, a system of equations linearized on a constant solution is constructed by a new technique. It is reduced to a symmetric form, the L^2-dissipativity of its solutions is proved, and a degeneration (with respect to the densities of the mixture components) of the parabolicity property for the original system is established. Actually, the system has the composite type. The obtained properties strictly reflect its physical correctness and dissipative nature of the quasi-hydrodynamic regularization.

Application of a hybrid large-particle method for calculating multicomponent gas mixture flows

Статья посвящена обобщению гибридного метода крупных частиц для численного моделирования течений многокомпонентных газовых смесей при наличии границ раздела газов с различными термодинамическими свойствами. Метод относится к алгоритмам сквозного расчета разрывов. Разностная схема является консервативной, однородной и имеет второй порядок аппроксимации по пространству и времени на гладких решениях. Результаты проверки на тестовых задачах в широком диапазоне чисел Маха и отношений газодинамических параметров подтвердили работоспособность метода. Выполнен анализ численных ошибок в окрестности контактных разрывов на сетках различного разрешения, свидетельствующий о сходимости результатов расчета к автомодельным решениям. This paper is devoted to a generalization of a hybrid large-particle method for the numerical simulation of multicomponent gas mixture flows in the presence of gas interfaces with various thermodynamic properties. The method belongs to the class of shock-capturing and interface-capturing algorithms. The employed difference scheme is conservative and uniform and possesses the second order approximation in space and time on smooth solutions. The obtained numerical results show the efficiency of the method in a wide range of Mach numbers and ratios of gas dynamic parameters. The error analysis performed near the contact discontinuities on grids of various resolutions confirms the convergence of numerical results to the self-similar solutions.