The Maxwellian Inflow distribution for the random variable z is defined as
where a is some real-valued parameter and erf denotes the error function. Note that for a = 0 the Maxwell Inflow distribution reduces to the Rayleigh distribution.
The Maxwellian Inflow distribution arises when implementing the inflow boundary condition for particles crossing a surface. Specifically, it is associated with the velocity distribution of particles, Maxwellian distributed in their moving frame of reference, that pass through a plane, a common boundary condition in molecular simulations of hydrodynamic flows in open systems.
Efficient algorithms for generating this distribution are discussed in: "Generation of the Maxwellian Inflow Distribution", A. Garcia, and W. Wagner, to appear in Journal of Computational Physics (2006). (PDF; Errata).
A C++ implementation of these algorithms, written by Mateusz RÝstad, may be
downloaded from the links below:
README (Software documentation for the routines)
MaxwellInflowGen.h (Main class)
generators.h (Individual classes for each Maxwellian Inflow generator)
Rnd.h (Classes for uniform and Gaussian generators)
Note that these routines use the Gnu Scientific Library (GSL); see the documentation for details.