Solutions Manual for Fundamentals of Open Channel Flow,
2nd Edition by Glenn Moglen (All Chapters) A+
Chapter 1: Introductory Material – Solutions
1.1. What slope would lead to a 1% difference between depth in the vertical plane rather than
depth measured perpendicular to the channel bottom? Compare this slope to the observation that
a channel slope of S0 = 0.01 m/m is generally considered quite steep for open channel flow.
Solution:
Comparing this number to a channel slope of S0=0.01 m/m we see that the slope corresponding
to a 1.0 percent difference between depths is more than an order of magnitude larger.
1.2. Using Bernoulli’s equation, write the energy balance in general terms for flow in an open
channel from location 1 to 2 where hL is the head loss between these two locations. Simplify the
equation by taking the perspective of a point on the water surface at both locations. Note: your
1
,Created By: A Solution
solution should show that the pressure term from Bernoulli’s equation is not relevant for open
channel flow.
Solution:
1.3. Parts (a), (b), and (c) require simple multiplication/division and/or addition/subtraction to
solve. The reader is cautioned to pay special attention to significant digits when reporting the
final answer.
a. If the density of water is 1000 kg/m3 and gravitational acceleration is 9.81 m/s2, what is
the unit weight of water?
b. /m3 and gravitational acceleration is 9.81 m/s2,
what is the unit weight of water?
c. The cross-sectional area of a channel is broken into three separate subareas with the
following sizes: 1.3 m2, 0.92 m2, and 15 m2. What is the total cross-sectional area of the
channel?
2
,Created By: A Solution
Solution:
Since density is given with one significant figure. The answer has one significant figure
resulting in: 10,000 N.
b) The new statement gives density with two significant figures, so the answer becomes:
9800 N.
c) The calculator-based sum of the three provided numbers is 17.22. However, the number
“15” indicates uncertainty in the “ones” place of the number. This same uncertainty needs
to be conveyed in the answer, so the correct answer is 17 m2.
1.4. The mean or bulk velocity of flow in a stream is observed to be 1.1 m/s. A rock tossed
into this same flow sets up ripples that radiate outward in all directions. It is noted that the
ripples propagating directly upstream travel at a velocity of 0.67 m/s in the opposite direction to
the direction of the flowing stream.
a. What is the Froude number for this flow?
b. Estimate the depth of flow in this stream.
3
, Created By: A Solution
Solution:
a) The wave velocity (velocity of ripple propagation) provided is the net velocity, equal to
the velocity of wave propagation in a still pool of water minus the bulk velocity downstream.
The wave velocity is 1.1 + 0.67 = 1.8 m/s. Using the definition of the Froude number:
b) The depth of flow in the stream can be estimated based on the wave velocity, vw = 1.8
m/s.
1.5. In the final chapter of this book, we study sediment transport. In a particular stream, it is
found that the sediment transport rate can be approximated as
W
4
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller ASolution. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $12.99. You're not tied to anything after your purchase.
