面源模式的通用算法探讨

提出了矩形面源扩散模拟计算的数值积分法和中心虚点源法，以及二者结合的综合法，并用算例进行了计算精度、计算速度和结果连续性的对比.结果表明:与传统的后置虚点源法及其改进算法——谷清经验法相比，该算法与理论真值的相对误差可从20%以上降低到3%以下，并且可以准确地反映风向和面源的形状，但在计算量上要增大十几倍到上百倍.对于任意不规则面源，提出了正方形分割算法，并对分割正方形的取舍采用简便的重心判断法，以准确方便地模拟其形状.综合运用笔者提出的适于机算的通用面源算法，对不同的计算任务权衡速度和精度采用合适的算法，可以处理各种气象条件下任意形状面源的扩散计算，并可取得理想的计算精度. 

A Discussion on the General Algorithm for Area-Source Air Pollution Dispersion Model

The digital-integral algorithm and central-fictive-point-source algorithm,along with their integrated algorithm were presented for rectangle shape area-source dispersion simulation.Using computing samples,the results of these algorithms were compared with those of traditional algorithm(including some other revised algorithm) in aspects of exactness,calculating speed and data consecutiveness.Compared with backward-fictive-point-source algorithm and its revised version,the algorithms proposed here can reduce the relative error from above 20% to below 3%,and can reflect the shape of source and wind direction variations.It also brings square-split algorithm for irregular-shape area source,and gives a new convenient judgment of square-cell position-by its barycenter.With balanced considerations of computer speed and precise demand of actual project,the synthetic application of these methods provides a general and precise computer-based algorithm for any shape of area sources.