Random walk to freedom: The time of effusion

The problem of effusion is studied using Monte Carlo simulations and scaling analysis. Particles confined to the interior of a container undergo a random walk with step size δ. If a hole is opened in one of the container walls, an outgoing diffusive current of particles will exit through it. Effusion is exponentially fast with the characteristic time dependent on δ, the container volume, and the size of the pore. It is found that if the effusion time is properly scaled, all the data can be collapsed onto one universal curve independent of the geometry of container and the pore.