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CIVIL-CATS
Monday, October 31, 2011
Wednesday, October 26, 2011
VELOCITY DISTRIBUTION IN OPEN CHANNEL
The measured velocity in an open channel will always vary across the channel section because of friction along the boundary. Neither is this velocity distribution usually axisymmetric (as it is in pipe flow) due to the existence of the free surface. It might be expected to find the maximum velocity at the free surface where the shear force is zero but this is not the case. The maximum velocity is usually found just below the surface. The explanation for this is the presence of secondary currents which are circulating from the boundaries towards the section centre and resistance at the air/water interface. These have been found in both laboratory measurements and 3d numerical simulation of turbulence.
The figure below shows some typical velocity distributions across some channel cross sections. The number indicates percentage of maximum velocity.
Figure of velocity distributions
To determine the values of ? and ? the velocity distribution must have been measured (or be known in some way). In irregular channels where the flow may be divided into distinct regions ? may exceed 2 and should be included in the Bernoulli equation.
The figure below is a typical example of this situation. The channel may be of this shape when a river is in flood – this is known as a compound channel.
Figure of a compound channel with three regions of flow
If the channel is divided as shown into three regions and making the assumption that ? = 1 for each then
Where
The figure below shows some typical velocity distributions across some channel cross sections. The number indicates percentage of maximum velocity.
To determine the values of ? and ? the velocity distribution must have been measured (or be known in some way). In irregular channels where the flow may be divided into distinct regions ? may exceed 2 and should be included in the Bernoulli equation.
The figure below is a typical example of this situation. The channel may be of this shape when a river is in flood – this is known as a compound channel.
Figure of a compound channel with three regions of flow
If the channel is divided as shown into three regions and making the assumption that ? = 1 for each then
Where
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Saturday, October 15, 2011
How to open MS Office 2007 file in Ms Office 2003
Hello World!!Well you may experience with a problem of opening Ms Office 2007 files [.docx, .xlsx,etc] in Ms Office 2003. This happens due to the compatibility difference between these two versions. It is obvious that difference is must between old and new versions. We can fix all these errors by adding the compatibility pack to the Ms Office 2003 which helps to run in low RAM too.
Download this Compatibility Pack from below servers:
