| Q.No. 02 Verify by computation the depth velocity relationships shown in figure below for the four flow regimes in a wide rectangular open channel. The |
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| temperature of the water is taken as 68°F. Depth Vs Velocity Chart |
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Figure 1 |
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| SOLUTION: |
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| For verification of type of depth velocity relationship first we will assume a wide |
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| rectangular channel with a constant width then we will take values of V and Y from |
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| the given figure and by calculations we will verify our assumptions |
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| Channel width |
= |
2 |
ft |
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| Flow range & type |
= |
Subcritical Laminar 1 |
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| Flow Velocity |
= |
0.2 |
ft/s |
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| Flow depth |
= |
0.02 |
ft |
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| Acc gravity |
= |
32.2 |
ft/s |
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| Hydraulic radius |
= |
0.0196 |
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| υ |
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= |
0.0000108 |
ft2/s |
@ 68F |
| Froud No |
= |
0.25 |
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| Rynold's No |
= |
364 |
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| For Froud's No 0.25 and Rynold's No 364 it can be verified from Figure.1, that Flow is in Subcritical Laminar 1 |
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| Channel width |
= |
2 |
ft |
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| Flow range & type |
= |
Supercritical Laminar 2 |
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| Flow Velocity |
= |
2 |
ft/s |
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| Flow depth |
= |
0.0025 |
ft |
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| Acc gravity |
= |
32.2 |
ft/s |
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| Hydraulic radius |
= |
0.0025 |
ft |
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| υ |
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= |
0.0000108 |
ft2/s |
| Froud No |
= |
7.05 |
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| Rynold's No |
= |
462 |
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| For Froud' No 7.05 and Rynold's No 462 it can be verified from Figure.1, that Flow is in Supercritical Laminar 2 |
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| Channel width |
= |
2 |
ft |
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| Flow range & type |
= |
Supercritical Turbulent 3 |
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| Flow Velocity |
= |
10 |
ft/s |
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| Flow depth |
= |
0.1 |
ft |
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| Acc gravity |
= |
32.2 |
ft/s |
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| Hydraulic radius |
= |
0.0909 |
ft |
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| υ |
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= |
0.0000108 |
ft2/s |
| Froud No |
= |
5.57 |
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| Rynold's No |
= |
84176 |
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| For Froud's No5.57 and Rynold's No 84176 it can be verified from Figure.1, that Flow is in Supercritical Turbulent 3 |
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| Channel width |
= |
2 |
ft |
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| Flow range & type |
= |
Subcritical Turbulent 4 |
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| Flow Velocity |
= |
0.25 |
ft/s |
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| Flow depth |
= |
0.1 |
ft |
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| Acc gravity |
= |
32.2 |
ft/s |
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| Hydraulic radius |
= |
0.0909 |
ft |
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| υ |
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= |
0.0000108 |
ft2/s |
| Froud No |
= |
0.14 |
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| Reynold's No |
= |
2105 |
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| For Froud's No 0.14 and Rynold's No 2105 it can be verified from Figure.1, that Flow is in Subcritical Turbulent 4 |
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Also See: Factors Affecting Water Hammer
