End of term3
What makes the nature of tangential stresses in turbulent flow more complex than in laminar flow?
Chaotic nature
What leads to the complexity of tangential stresses in turbulent flow?
Chaotic mixing
What conditions the magnitude τ ̅ in turbulent flow according to the provided statements?
Pulsation velocity additives
Why are statistical methods required to establish dependencies in turbulent flow?
Chaotic nature of flow
What theories are used for a quantitative description of turbulent motion?
Empirical turbulence theories
What is the dynamic coefficient of turbulent viscosity (μ_T) dependent on?
Turbulent mixing intensity
Which theory is considered the most widely used among semi-empirical turbulence theories?
Prandtl's theory
Where are viscous stresses considerably smaller than turbulent stresses, according to Prandtl's theory?
Far from the wall
What is the first region into which the flow is divided according to Prandtl's theory?
Laminar sublayer
What did Prandtl refer to as the distance traveled by an eddy until it loses its individual characteristics?
Mixing length
What must be determined empirically through experimentation in Prandtl's theory?
Mixing length
What is Prandtl's theory termed due to the need for empirical determination of mixing length?
Empirical
How does the dynamic coefficient of turbulent viscosity (μ_T) change across the pipe section?
Sharply
In the region of developed turbulent motion, where is μ_T significantly larger than molecular viscosity μ?
Far from the walls
What is the main consideration when assessing hydraulic losses in industrial pipelines with natural
roughness?
Shape of roughness protrusions
What does the Murin diagram not exhibit, contrary to Nikuradze's curves?
Dip characteristic
What is considered when determining relative roughness (ε)?
Radius of the pipe
What is inversely proportional to relative roughness (ε)?
Relative smoothness
What does the Blasius line for smooth pipes describe in the zone of hydraulically smooth pipes for
turbulent flow?
Quadratic resistance law
What characterizes the laminar flow zone according to the Reynolds number (Re)?
Re < 2300 or lg Re < 3.6
In the transition zone, what happens to the friction factor (λ) with an increase in Reynolds number?
Increases
What does the zone of rough pipes (𝒓𝟎∕𝜟 < 500) correspond to in turbulent flow?
Sub-quadratic zone
What happens to the friction factor (λ) in the zone of fully rough pipes as Reynolds number increases?
Becomes independent of Re
What is considered insufficient when assessing pipes with natural roughness?
Height of roughness protrusions
What is meant by equivalent roughness (𝜟) in hydraulic reference books?
Grainy roughness
According to Nikuradze's experiments, what is the influence of wall roughness on friction coefficient (λ) in
the transitional region?
Larger values
What parameters is the friction coefficient (λ) considered a function of in turbulent fluid motion?
Reynolds number and relative roughness (ε)
What are the two key questions addressed when studying turbulent fluid motion in pipes?
Head losses and velocity distribution
What significantly influences head losses and velocity distribution in turbulent fluid motion?
Pipe diameter, fluid viscosity, flow velocity, and wall roughness
What does the Reynolds number range (Re) below 2300 suggest about the resistance (friction coefficient)
in laminar flow?
Proportional to velocity