MaxwellBoltzmannDistribution.h File Reference

#include <array>
#include <random>

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Functions
std::array< double, 3 >	maxwellBoltzmannDistributedVelocity (double averageVelocity, size_t dimensions)

Function Documentation

maxwellBoltzmannDistributedVelocity()

std::array<double, 3> maxwellBoltzmannDistributedVelocity	(	double	averageVelocity,
		size_t	dimensions
	)

MaxwellBoltzmannDistribution.h

Date

: 13.12.2019

Author

: F. Gratl Generate a random velocity vector according to the Maxwell-Boltzmann distribution, with a given average velocity.

Parameters

averageVelocity	The average velocity of the brownian motion for the system.
dimensions	Number of dimensions for which the velocity vector shall be generated. Set this to 2 or 3.

Returns

Array containing the generated velocity vector.

Definition at line 3 of file MaxwellBoltzmannDistribution.cpp.

                                                                                                   {
    // we use a constant seed for repeatability.
    // random engine needs static lifetime otherwise it would be recreated for every call.
    static std::default_random_engine random_engine(10242);
 
    // when adding independent normally distributed values to all velocity components
    // the velocity change is maxwell boltzmann distributed
    std::normal_distribution<double> normal_distribution{0, 1};
    std::array<double, 3> random_velocity{};
    for (size_t i = 0; i < dimensions; ++i) {
        random_velocity[i] = averageVelocity * normal_distribution(random_engine);
    }
    return random_velocity;
}