online_wsprofiles_25:   S2 water-surface profile Main page Example Summary Reference Disclaimer DESCRIPTION General The php script [program]   online_wsprofiles_25   calculates an S2 water-surface profile in a prismatic open channel using the direct-step method (Chow, V. T.: Open-channel hydraulics, McGraw-Hill, 1959). The program calculates critical and normal depths based on the geometric and hydraulic input data. Newton's iteration is used to solve the nonlinear equations. An S2 profile is subnormal, supercritical, and steep (see figure). The calculated gradually varied flow depth varies between the specified flow depth at the upstream boundary [or, if requested, the calculated critical depth for the upstream channel] and [it is asymptotic to] normal depth downstream. Input There are five required input variables:   discharge Q, bottom width B, side slope z, Manning's n, and bottom slope So. For the upstream boundary condition, you can specify a suitable input flow depth. Alternatively, if the input flow depth box is left blank, the program will use critical depth [in the upstream channel] instead. The program echoes the input data. Internally calculated critical and normal depth are echoed with five-decimal (5) accuracy. Defaults For the input flow depth, you can enter any suitable supercritical subnormal flow depth. The allowable range of input flow depth is the following: Less than [or equal to] critical depth [upstream], and greater than or equal to normal depth (plus 0.002 m) downstream. Leave this box blank if you want the program to use critical depth. You can enter the desired number of computational intervals n. The suggested range is 50-200. A higher number means higher computational accuracy. Leave this box blank if you want the program to set the default value at 100. You can enter the desired number of tabular output intervals m. The suggested range is 10-100. A higher number means more detailed [longer] output. Leave this box blank if you want the program to set the default value at 10. Output A table with thirteen (13) columns: output interval index k, [flow] depth (m), [flow] area (m2), velocity (m/s), velocity head (m), specific head (m), wetted perimeter (m), hydraulic radius (m), friction slope (m/m), average [friction] slope (m/m), specific head difference (m), length increment (m), and total [channel] length (m). The number of computational intervals n and the number of tabular output intervals m are printed for reference. The calculated normal depth and normal-depth Froude number are printed for reference. If the normal-depth Froude number is less than 1.02, execution is halted (See Error message No. 8 below). Units The current version is written in SI [metric] units. Errors Enter only positive [nonzero] numbers for discharge, Manning's n, and bottom slope (for suitable practical ranges, see error messages Nos. 4 and 5). Failure to do this will trigger an error message and halt execution (Error messages No. 1: A, B, and C, respectively). Enter only nonnegative [zero or greater] numbers for bottom width and side slope. Failure to do this will trigger an error message and halt execution (Error messages No. 2: A and B, respectively). Bottom width and side slope cannot be zero at the same time. Failure to do this will trigger an error message and halt execution (Error message No. 3). A Manning's n value outside of the range 0.008-0.250 will trigger an error message and halt execution (Error message No. 4). A bottom slope outside of the range 0.001-0.3 will trigger an error message and halt execution (Error message No. 5). Enter only nonnegative numbers [zero or greater] for discharge, bottom width and side slope in the upstream channel. Failure to do this will trigger an error message and halt execution (Error messages No. 6: A, B, and C, respectively). Caution: Do not specify an [actual] zero upstream bottom width Bu/s (a triangular cross section) when the downstream channel bottom width B is other than zero. Likewise, do not specify an [actual] zero upstream size slope zu/s (a rectangular cross section) when the downstream channel side slope z is other than zero. In either case, the upstream values will be redefined as equal to the specified nonzero downstream values. An input flow depth greater than the calculated critical depth or less than or equal to the calculated normal depth will trigger an error message and halt execution (Error messages No. 7: A and B, respectively). A normal-depth Froude number less than 1.02 will trigger an error message and halt execution (Error message No. 8). Thank you for running online_wsprofiles_25.   Please call again.   [Version 1.0.0,   070502]