Front problem, adaptive grid

Here the constant C takes care of the relative importance of the second derivative influence. Instead of solving a front problem in the coordinates (x,t) (physical space) we perform the calculations in the computational space (C t). For one dimensional problems this adaptive grid transformation proved to be very successful. We can perform a transformation in a similar spirit for a two dimensional domain (x,y,t) -> A general sketch of this transformation... 

Typically, the numerical solutions techniques used are very specific to the problem. Particularly challenging problems include moving front problems where concentration profiles, for example, may vary widely over a short distance but may not change much at other spatial locations. The spatial discretization must be small close to the front for accuracy and numerical stability, but must be larger at other locations to reduce computation time. Various adaptive grid techniques to change the spatial step sizes have been developed for these problems. One of the more common codes to solve fluid-flow-related problems is FLUENT. 

For a more general strategy, the use of dynamically adaptive grids has been proposed by several authors [4, 5] as a more suitable and (in some cases) more efficient solution for the problem of moving reaction fronts. The... 

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