Which example illustrates a uniform but unsteady flow in fluid dynamics?

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BHEL Supervisor Trainee Mechanical 21 Jan 2024 Official Paper

Answer 1

Explanation:

Uniform but Unsteady Flow in Fluid Dynamics

In fluid dynamics, a uniform flow refers to a flow in which the velocity of the fluid at any given point in the space does not vary with position. However, in an unsteady flow, the velocity can vary with time. Therefore, a uniform but unsteady flow is one where the fluid velocity is the same at every point in the space at any given instant but can change over time.
In a uniform but unsteady flow, the primary characteristic is that the flow parameters (e.g., velocity, pressure) are the same at every point in a given cross-section at any instant.
However, these parameters can change as time progresses.
This type of flow is often seen in situations where external conditions influencing the flow change over time, such as varying wind speeds or fluctuating pressure conditions.

Smoke rising uniformly but varying in velocity from a chimney over time.

This option correctly illustrates a uniform but unsteady flow. The smoke rises uniformly, meaning its velocity is consistent across any horizontal cross-section at a given height at any instant. However, the velocity of the smoke changes over time, indicating that the flow is unsteady. This can happen due to changes in the temperature of the chimney, variations in the wind speed, or other external factors affecting the velocity of the smoke.