Collision model for air

The dataset contains:

• Results of classical trajectory calculations (CTC) of binary intermolecular collisions of the following pairs of diatomic molecules:
  • N2 - N2
  • N2 - O2
  • O2 - O2
• Collision model code (C++ class)

1. CTC results

Files with the results of calculations are presented below as files with names "NNNN_md_distr_XX.csv", where NNNN corresponds to a pair of colliding molecules, XX corresponds to the following parameter P after collision:

• 00: γ'_r
• 01: γ'_1
• 07: g'_x, m/s
• 08: g'_y, m/s
• 09: g'_z, m/s

List of fields inside a file:

• ε/k, K
• b, A
• γ_r
• γ_1
• Mean value of the P
• After the symbol "d", the probability density for P is stored

Results of trajectory MD calculations

Post-collision value	N2‒N2	O2‒O2	N2‒O2
γ_r	Download	Download	Download
γ_1	Download	Download	Download
g_x	Download	Download	Download
g_y	Download	Download	Download
g_z	Download	Download	Download

2. Collision model code

The proposed collision model was implemented as a C++ class:

• collisionmodel.h
• initialization file for N2-N2 collmodel_N2_N2.txt
• initialization file for O2-O2 collmodel_O2_O2.txt
• initialization file for N2-O2 collmodel_N2_O2.txt

Before use, it is necessary to initialize once the model from the file:

        #include "collisionmodel.h"
        
        // Model class
	collisionmodel cm;

	// Init model from file
	cm.LoadModelFromFile("collmodel_N2_N2.txt");

To calculate the post-collision parameters of the colliding molecules, you need to call the function ComputeCollision(...) with the the pre-collision parameters as arguments:

        // Pre-collision values
	double b = ...;
	double er_before = ...;
	double ein_before[2] = {...};

        // Post-collision values
	double er_after, ein_after[2], chi;

        // Compute post-collision parameters
	cm.ComputeCollision(b, er_before, ein_before, &er_after, ein_after, &chi);

Related Publication

Artem Yakunchikov, Vasily Kosyanchuk, Aliya Iuldasheva, Rotational relaxation model for nitrogen and its application in free jet expansion problem // Physics of Fluids 32, 102006 (2020) https://doi.org/10.1063/5.0021704

Acknowledgments

The research is carried out using the equipment of the shared research facilities of HPC computing resources at Lomonosov Moscow State University and Joint Supercomputer Center of the Russian Academy of Sciences. The research was supported by the Russian Foundation for Basic Research (project № 18-31-20025).