GATE questions from Hydrology - GATE PSUs preparation -part 10

Hi,
Here are few statements from Hydrology which has made their place in GATE Civil Engineering(CE). The bold letter represents the answer which are absent in actual question.

Fluid Mechanics- one liners- GATE preparation - part 2

Here is a list of one liners which can be useful for your Civil Engineering GATE examination.

1. The equation T= -(dP/dl).r/2 for flow through circular tubes, where T is shear stress at distance r from center, is applicable for both laminar and turbulent flow.
2. A fluid is a substance that can not remain at rest when subjected to a shearing force.
3. One end of a two dimensional water tank has the shape of a quadrant of a circle of radius 2m. When the tank is full, the vertical component of the force per unit length on the curved surface will be 1000.kg.pi.f. (pi = 3.14)
4. If mean velocities at two ends of a stream tube 10 cm apart are 2.5 m/sec and 3 m/sec then convectional tangential acceleration mid-way will be 13.75 m/sec^2.
5. When a particular discharge is flowing in a horizontal pipe, a mercury water U-tube manometer connected to entrance and throat of a Venturi-meter fitted in the pipe recorded a deflection of 25 cm. If the same discharge flowed through the same pipe kept at an i…

Classification of fluids

All the engineering fluids can be classified into two broad classes and then further sub-classes as follows:
(1) Newtonian fluids
(2) Non- Newtonian Fluids
Newtonian Fluids: These are the fluids which follow the Newton's law of viscosity. So shear stress of the fluids is directly proportional to the the velocity gradient, so it varies linearly with it. Newtonian fluids have constant viscosity which does not depend upon the stress. Sometimes it may vary under some specific conditions when the velocity gradient changes with the layer to layer.

Non- Newtonian Fluids: These fluids exhibit non-Newtonian characteristics, i.e. shear stress is not linearly dependent upon the velocity gradient, so doesn't follow the Newton's law of viscosity.
T = A.(du/dy)^n + B ; Where A and B are constants which depend upon type of fluid and conditions imposed on the flow. Value of n is 1 and of B is 0 for the Newtonian fluids.  n is also known as power index, and depending upon its value non-Newto…

Comparison of Kennedy's and Lacey's Theories

Hello,

Here is a brief comparison of Kennedy's theory and Lacey's theory for the design of channels for canal etc.

The concept of silt transportation is same in both the cases, both agree that the silt is carried by the vertical eddies generated due to friction of the flowing water against rough surface of canal. Kennedy considered a trapezoidal channel section and, therefore, he neglected eddies generated from the sides. For this reason, Kennedy's critical velocity formula was derived only in terms of depth of flow(y).  Lacey considered that an irrigation channel achieves a cup-shaped section(semi-ellipse) and that entire wetted perimeter of the channel contributes to the generation of silt supporting eddies. He, thus, used hydraulic mean radius(R) as a variable in his regime velocity formulas instead of depth(y).Kennedy stated all the channels to be in state of regime provided they did not silt or scour. But Lacey differentiated between two regime conditions, i.e. initia…