|
Based upon the Naiver-Stokes equation and the continuity equation, to use the MAC (Marker and Cell) method, coupled with a height function to investi-gate and analyze the flow over a broad-crested weir. There are four types of weir, i.e., the long weir, broad crested weir, narrow-crested weir, and the sharp-crested weir, and the classification is based upon the ratio of the upstream depth H to the longitudinal width of the weir L. Within this range of ratio of a broad-crested weir flow, results of simulated flows with be compared with both the theoretical redictions and the previous works, such as the discharge coefficient, the pressure distribution, the velocity profile, the shear stress and the free surface etc.. The agreement of comparisons has been found, if appropriate values are chosen for cofficients which are inherent in the numerical scheme, such as the upstream weight coefficient and the relaxation factor. The MAC method use the height function in stead of the spreading particles to trace the location of the free surface, and the requirement of this technique is that the slope of the spreading particles to trace the location of the free surface, and the requirement of this technique is that the slope of the free surface must be less than that of the disgonal of the cell. Channel flows which are suitable to analyze by making use of this technique are the weir flow, the flow of free overfall, the sluice gate flow etc..
|