Question

In: Mechanical Engineering

In a curved channel, what causes the asymmetry in the full flow speed profile?

In a curved channel, what causes the asymmetry in the full flow speed profile?

Solutions

Expert Solution

In a channel with bed topography that does not vary in the downstream direction, a secondary circulation composed of outward flow at the surface and inward flow near the bottom extends across the entire width. If the curvature is constant, the cross?stream velocity component near the bed and the pattern of boundary shear stress can be estimated by assuming fluid accelerations to be small. Unfortunately, this procedure cannot be used in analyzing the flow through natural river meanders, or through channels with downstream constant bottom topography but with rapidly changing curvature. In these latter cases, effects arising from bed? and bank?induced momentum changes must be accounted for. Evidence for a substantial topographically induced alteration in the cross?stream flow pattern relative to that for the analogous constant bottom topography case is provided through new analyses of several sets of laboratory and field data. Shoaling over the point bar in the upstream part of the bend is shown to force the high?velocity core of the flow toward the pool. This is accomplished by a convective acceleration?caused decrease in the cross?stream water surface slope and a resulting dominance of the vertically averaged centrifugal force. The primary effect is a velocity component toward the outside or concave bank throughout the flow depth over the upstream, shallow part of the point bar and an outward component of boundary shear stress in this region. The channel curvature?induced inward component of boundary shear stress consequently is confined to 20 or 30% of the channel width at the pool. Outward transfer of momentum over the point bar, as manifested by a rapid crossing of the high?velocity core from the inside bank to the outside one, contributes to an enhanced decrease in boundary shear stress along the convex side of the stream as the top of the bar is approached. Forces arising from topographically induced spatial accelerations are of the same order of magnitude as the downstream boundary shear stress and water surface slope force components, so they must be modeled as zero?order, not first? or second?order, effects.


Related Solutions

What equations are/can be used to describe the velocity profile for a turbulet flow in a...
What equations are/can be used to describe the velocity profile for a turbulet flow in a pipe and how do you visualise the plot in excel?
You are offered to invest in a project with the following cash flow profile. What is...
You are offered to invest in a project with the following cash flow profile. What is the future worth (i.e., at t = 10) of this investment to you if your MARR is 7%? t 0 1 2 3 4 5 6 7 8 9 10 $ in million -10 0 0 0 0 5 5 5 5 5 7.5 A. $20.1 million B. $18.6 million C. $16.1 million D. $14.6 million My answer is B but I just want...
A horizontal jet of oil (SG = 0.6) strikes a curved blade that turns the flow...
A horizontal jet of oil (SG = 0.6) strikes a curved blade that turns the flow through an angle of 1800. The jet area is 1000 mm2 and its speed from a stationary nozzle is 35 m/s. The blade is moving toward the nozzle at 15 m/s. Determine the force on the blade from the jet (a) in horizontal direction, Rx in kN and (b) in vertical direction, Ry in kN. [Consider the relative jet velocity in calculations]
a) What is brain asymmetry/lateralization? b)what is importance of brain asymmetry/lateralization for higher cortical functions? please...
a) What is brain asymmetry/lateralization? b)what is importance of brain asymmetry/lateralization for higher cortical functions? please check plagiarism
In a uniform open channel flow: The total energy remains constant along the channel The total...
In a uniform open channel flow: The total energy remains constant along the channel The total energy line either rises or falls along the channel depending on the state of the flow The specific energy decreases along the channel The line representing the total energy is parallel to the bed of the channel In which of the following situations, the flow is uniform? Flow in channel contraction or expansion Flow in the vicinity of a bridge pier Flow at the...
1. What’s information asymmetry? 2. What problems could arise because of information asymmetry? 3. What methods...
1. What’s information asymmetry? 2. What problems could arise because of information asymmetry? 3. What methods does a lender use to address adverse selection problem? 4. What methods does an insurance company use to address moral hazard problem?
A dentist causes the bit of a high-speed drill to accelerate from an angular speed of...
A dentist causes the bit of a high-speed drill to accelerate from an angular speed of 1.46 x 104 rad/s to an angular speed of 3.29 x 104 rad/s. In the process, the bit turns through 3.02 x 104 rad. Assuming a constant angular acceleration, how long would it take the bit to reach its maximum speed of 9.56 x 104 rad/s, starting from rest?
What are some reasons for various errors in the open channel flow experiment(fluid mechanics)?
What are some reasons for various errors in the open channel flow experiment(fluid mechanics)?
What is "spherical aberration" in a curved mirror and what is the reason for it? What...
What is "spherical aberration" in a curved mirror and what is the reason for it? What can be done to avoid it?
What is the aluminum profile? What is the manufacturing method of aluminum profile? What are the...
What is the aluminum profile? What is the manufacturing method of aluminum profile? What are the materials used in the manufacture of the product, describe in detail. What are the stages of the production method? What are the faults that can be caused by the production in the product? Are there any alternative production method? What are those, compare them. What are the standards to follow in the production method?
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT