For the simulation of transport processes in porous media effective parameters for the physical processes on the target scale are required. Numerical upscaling, as well as multiscale approaches can help where experiments are not possible, or hard to conduct.

We consider a singularly perturbed boundary value problem with two small parameters. The problem is numerically treated by a quadratic spline collocation method. The suitable choice of collocation points provides the discrete minimum principle. Error bounds for the numerical approximations are...

A variation of Rosenstock's trapping model in which N independent random walkers are all initially placed upon a site of a one-dimensional lattice in the presence of a one-sided random distribution (with probability c) of absorbing traps is investigated. The probability (survival probability)...