An Automated Hand Over Criteria For Sub Grid Plume Models
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Date
2002-06-26
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Abstract
An algorithm for developing a transfer criteria from sub-grid plume models to standard Regional Air Quality Models (RAQM) is presented. The physical sizes of pollutant plumes emnating from sources are relatively small when compared to the grid size of RAQM. Hence the plume is allowed to grow in a sub-grid refined mesh until it is sufficiently large enough to be resolved by the grid cells of RAQM. Information coming from the sub-grid plume model must be blended effectively into the regional model.
The central issues in developing the hand-over criteria have been identified. A knowledge of dynamic and chemical evolution of the plume is essential to prevent the degeneration of significant information. The hand-over criteria must have a foundation in the mathematical characterstics of the algorithm and include analysis of both mesh and modeled terms influence for both fine and coarse grids. The transfer criteria is based on the fact that the computational mesh is a band-pass filter and thereby restricts the frequencies that may bypass in the solution.
Various cross-sections of numerically simulated plume data are subjected to Fourier analysis to determine when the transfer to the RAQM mesh is appropriate. An energy measure is used to quantify the loss of information that occurs during the transfer process.
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Keywords
Fourier Frequencies, Hand-Over Criteria, Sub-Grid Plume Models, Regional Air Quality Models (RAQM), Band-Pass Filter
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Degree
MS
Discipline
Mechanical Engineering
