The simulations conserve total fluid volume exactly, and total energy and angular momentum to within a few percent. The front is well-defined in all cases, and the numerical solutions agree quite well with the few known analytical solutions. Parallel processing makes this approach practical. Nearly linear speed-up is obtained with up to 16 processors. Doubling to 32 processors produced a speed-up of nearly 50 percent.
Load balancing is an important issue as well.
The speed-up from four to eight processors is better than a factor of two, because optimal load balancing for this particular simulation requires approximately seven processors assigned to the lower layer for every one assigned to the upper layer. Rather, the problem size is the same in all cases. There are at least two operational roles for PIC models. First, they can be embedded in regional scale models to predict the evolution of fronts and other flow structures on scales inaccessible to the larger scale model. Second, PIC models are capable of assimilating high resolution data from active and passive satellite sensors and interpolating this data consistently to the coarse scale model grids.