The study of time dependence of particle flux with multiplication in a random medium

Algorithms of Monte Carlo method for estimating probabilistic moments of the parameter of time exponential asymptotics of particle flux with multiplication in a random medium are constructed. It was analytically and numerically shown that the asymptotics of the mean number of particles is close to an exponential one with the factor containing a summand proportional to square of time.

Three-dimensional capillary waves due to a submerged source with small surface tension

Steady and unsteady linearised flow past a submerged source are studied in the small-surface-tension limit, in the absence of gravitational effects. The free-surface capillary waves generated are exponentially small in the surface tension, and are determined using the theory of exponential asymptotics. In the steady problem, capillary waves are found to extend upstream from the source, switching on across curves on the free surface known as Stokes lines. Asymptotic predictions are compared with computational solutions for the position of the free surface. In the unsteady problem, transient effects cause the solution to display more complicated asymptotic behaviour, such as higher-order Stokes lines. The theory of exponential asymptotics is applied to show how the capillary waves evolve over time, and eventually tend to the steady solution.