688 MODELS IN HYDRAULIC ENGINEERING
Solution
- Utilizing fully the discharge capacity gives a discharge scale 4
106 /27148 150. From equation (16.7), Mh(MQ/Ml)2/3(148 150/
250)2/370.57. Therefore let us choose Mh75, giving a distortion of
3.33, which is probably quite acceptable in this case.
- MQMh3/2Ml 75 3/2 250 162 380. The maximum model discharge
will be 4 106 /162 38024.6 l s^1.
- MtMl/MMlMh^ 1/2250/751/228.87 (equation (16.3)).
- MwsMh3/2/Ml 75 3/2/2502.6 (equation (16.13)).
- From the Manning–Strickler equation for a wide channel with Ry,
MMn^1 Mh2/3M1/2s Md^ 1/6Mh2/3Mh1/2Ml^ 1/2Md^ 1/6Mh7/6Ml^ 1/2Mh1/2,
MdM^4 hM^ l^3 754 /250^3 2.0252.
6.
M∆
2
11.11 (equation (16.12)).
Note that the answer to 5 assumes that there is no effect of bedforms (i.e.
that the bed is flat) which may be unrealistic; this has to be checked by
further computation, and the final value of Mdmay influence the whole
model design.
References
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—— (1988) Turbulence modelling of surface water flow and transport, Part I–V;
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250
75
M^2 l
M^2 h
M^2 hM^3 l
M^4 hMl
M^2 h
MlMd
