MAI and ITAM of RAS created a unique solution for calculations in gas dynamics

23 April 2021

 MAI and ITAM of RAS created a unique solution for calculations in gas dynamics
At the end of 2020, a research team from the Moscow Aviation Institute and the S. A. Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences completed a two-year project on the development of computational gas flow modeling methods for external and internal problems. S. A. Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences (ITAM SB RAS) completed a two-year project on the development of methods for computer modeling of gas flows as applied to external and internal aerodynamics problems. The project was supported by the Russian Foundation for Basic Research.

As part of the project, the research team developed an original set of software codes that allow solving fundamental and applied problems of a wide range of gas flow regimes: from slow to hypersonic, from gas flows under normal conditions to rarefied and free-molecular regimes. This range of developed software packages can be used for mathematical simulation of space and hypersonic aircraft, as well as for simulation of microelectromechanical (MEMS) devices.

Why is the issue of computer modeling of gas flow so important? Creating a mathematical model is known to be incomparably more cost-effective than running an experiment. When designing an aircraft, you need to calculate in advance what temperatures it should withstand, what material to use, what is the best geometry for flowing gas. When designing a microdevice, it is important to calculate its carrying capacity and, therefore, its dimensions.

One of the three co-authors of the project is Maxim Timokhin, a candidate of physics and mathematics, associate professor at 801 "Physics" Institute № 8 "Information Technology and Applied Mathematics" MAI. During the work, the authors conducted comparative calculations by three methods: using Navier-Stokes equations, the Monte Carlo method of direct statistical modeling, as well as a unified gas-kinetic scheme based on Shakhov's equation. Maxim Yurievich's calculations were carried out using the computing resources of Institute No. 8 "Information Technologies and Applied Mathematics" of the MAI and were aimed at investigating the distribution of total enthalpy within the shock wave.

"A wide range of software-implemented continuum and kinetic methods for numerical modeling of various gas-dynamic flow regimes has been assembled during the project. Existing software codes have been upgraded and the applicability of each method to several fundamental gas dynamics problems has been investigated. For example, the shock wave structure problem and the shock wave regular reflection problem," says Maxim Timokhin.
Enthalpy is a thermodynamic function that characterizes the energy state of a system under constant pressure. Before and after the shock wave, enthalpy remains unchanged. A shock wave is characterized by a jump in the medium's parameters: density, pressure, temperature, velocity. An illustrative example is an entry of a spacecraft into the upper atmosphere when there is an abrupt change in the dynamics of a rarefied gas, where the classical equations of hydroaerodynamics stop working. Work on this question has been carried out since the inception of the space industry, but the enthalpy behavior inside the shock wave has so far been little investigated.

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