Consider the following statements comparing turbulent boundarylayer wi...
Statement 1: Turbulent boundary layers are thicker than laminar boundary layers.
Turbulent boundary layers are indeed thicker than laminar boundary layers. This is because turbulence introduces additional mixing and momentum transfer, causing the flow to spread out and increase in thickness. In contrast, laminar flow is characterized by smooth and orderly movement, resulting in a thinner boundary layer.
Statement 2: Velocity in turbulent boundary layers is more uniform.
This statement is incorrect. In a turbulent boundary layer, the velocity is highly fluctuating and chaotic. The presence of eddies and vortices in turbulent flow causes uneven distribution of velocity across the boundary layer. On the other hand, in a laminar boundary layer, the velocity profile is more uniform and predictable.
Statement 3: In the case of a laminar boundary layer, the thickness of the boundary layer increases more rapidly as the distance from the leading edge increases.
This statement is correct. In a laminar boundary layer, the thickness of the boundary layer increases rapidly as the distance from the leading edge increases. This is due to the development of a velocity gradient in the flow, leading to an increase in the boundary layer thickness. The growth of a laminar boundary layer is governed by the boundary layer equation, which predicts a rapid increase in thickness with distance.
Statement 4: For the same local Reynolds number, shear stress at the boundary is less in the case of a turbulent boundary layer.
This statement is correct. In turbulent flow, the shear stress at the boundary is higher compared to laminar flow. This is because turbulence introduces additional mixing and momentum transfer, resulting in increased shear stress. Higher shear stress in turbulent flow contributes to higher drag forces on surfaces. In laminar flow, the orderly movement of fluid particles leads to lower shear stress at the boundary.
Conclusion:
Based on the analysis, we can conclude that statements 1, 3, and 4 are correct, while statement 2 is incorrect. Therefore, the correct answer is option A, where all the correct statements are included.
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