The discharge coefficient of SMBF flumes under free and submerged conditions

In this study, the discharge coefficients ( C d ) of SMBF flumes under free and submerged flow conditions were analytically investigated. The dimensionless parameters involved in the discharge coefficient, derived from the dimensional analysis, are the contraction ratio [ r crn = ratio of flume width ( w ) to channel width ( B )], relative head ( h w : the ratio of the upstream head ( h ) to the w ) and, in the case of submerged flow, also the submergence ratio [ S_r = h_t /h_u : downstream flow depth ( h_t ) to upstream flow depth ( h u )]. C d decreases logarithmically from 1.2 to 0.75 in the range of h_w between 0.4 and 1.8. The submerged condition does not reduce the C_d , but it reduces the discharge capacity (up to 50