有关粉尘释放模型的应力分配模式存在问题的讨论

Problems of the Shear Stress Partition Sub-models of a Dust Production Model

准确模拟粉尘释放通量对评价粉尘气溶胶的气候效应、沙漠化和沙尘暴防治具有重要意义。敏感性试验、室内和野外风洞实验表明被广泛使用的DPM(Dust Production Model)粉尘释放模型的2个应力分配模式———Marticorena模式和A lfaro模式存在明显问题:由于目前空气动力学粗糙度模式还不能考虑粗糙元间隙率和粗糙元分布状况空气动力学粗糙度的影响,以空气动力学粗糙度为主要参数的Marticorena模式和A lfaro模式还不能考虑粗糙元间隙率和粗糙元分布状况对应力分配的影响,而相关实验表明这些因素对应力分配存在显著影响;Marticorena模式和A lfaro模式预测的应力分配系数和起动摩阻风速存在显著差异,目前实验结果还不能判断二者正确与否;Marticorena模式和A lfaro模式预测的能够有效控制风蚀的应空气动力学粗糙度与实际观测相矛盾。针对上述问题提出了通过风洞实验改进当前应力分配模式的主要途径。

Simulation of dust emission flux is very fundamental for evaluating climatic effects of dust aerosols and controlling desertification process and dust storm. The two shear stress partition models were proposed by Marticorena and Alfaro respectively for evaluating effect of roughness elements on dust production. The existing problems of them are discussed on basis of sensitive tests, previous wind tunnel and field experiments. First, the influence of porosity and spatial heterogeneity of roughness elements on shear stress partition was not taken into account because all equations about roughness length can not involve such factors as porosity and spatial heterogeneity of roughness elements. However, it is proved that these factors cannot be neglected by many experiments. Second, the result from sensitive test of Marticorena＇s Model is in disagreement with that of Alfarog Model, implying that the models need to be investigated further by wind tunnel experiment. Third, regarding the roughness length to efficiently suppress wind erosion, the values predicted respectively by the models are questioned by some wind erosion experiment data, therefore the relationship between shear stress partition and roughness length need to be reassessed. In terms of these problems of the models, two approaches are proposed ： improving roughness length formula and tuning empirical constants of the models by wind tunnel experiment.