Study on improving the numerical stability in reverse simulation

Nowadays, reverse simulation seems to be a promising topic in term of environment research. Mathematically, reverse simulation is the solution of the transport equation in the negative time advancing. The process of transport equation is equivalent to that of positive time advancing with negative convection and diffusion. However, there is a numerical instability problem in solving diffusion term. This research introduces a method to improve numerical stability in reverse simulation. Two examples are given in this paper. In the first one, a simple laminar flow is considered and pollutant is emitted for uniformity time. In the second example, the wind flow around a single building is considered. (author)