Fluid Mechanics Sheet 17
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1) Question.
The critical state of flow through a channel section may be defined as the state of flow at which the -
Answer. -
2) Question.
A triangular channel section is most economical when each of its sloping sides is inclined to the vertical at an angle of -
Answer.A triangular channel section is most economical when its sloping sides are inclined to the vertical at an angle of 45 degree. This occurs when the channel has the minimum wetted perimeter for a given cross-sectional area, a condition known as hydraulic efficiency.-
Geometric Condition:The most economical triangular section has a right-angled vertex angle (a total angle of90?), meaning each side slope forms a 45? angle with the vertical.
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3) Question.
For maximum discharge in a circular channel section, the ratio of the depth of flow to that of diameter of the channel is -
Answer. -
4) Question.
The depth of flow for maximum velocity in a circular channel section with diameter equal to 1.5 m is -
Answer. -
5) Question.
The Chezy's coefficient -
Answer.
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6) Question.
For uniform flow in a channel -
Answer. -
7) Question.
For shooting flow the Froude number is -
Answer.For shooting flow (also called supercritical flow), the Froude number is greater than 1. This means the flow velocity is greater than the speed of a surface wave, preventing any disturbance from traveling upstream.- Froude number > 1: Supercritical or shooting flow. The velocity is high and the depth is low.
- Froude number = 1: Critical flow. This is the transition point between subcritical and supercritical flow.
- Froude number < 1: Subcritical flow or tranquil flow. The velocity is low, wave speed is greater than the flow velocity, and disturbances can travel upstream.
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8) Question.
The flow in channels is considered to be in transitional state if the Reynolds number is -
Answer. -
9) Question.
In a gradually varied flow -
Answer.In gradually varied flow, the slopes of the Energy Grade Line (EGL) and Hydraulic Grade Line (HGL) are typically not the same, except under the specific condition of uniform flow in a prismatic channel. -
10) Question.
The hydraulic jump always occurs from -
Answer.A hydraulic jump is the rapid transition from supercritical (high-velocity, shallow) flow to subcritical (low-velocity, deep) flow.
Supercritical ⇒ depth (below critical depth), subcritical ⇒ (above critical depth). So jump is from below → above critical depth.