A flow field satisfying ⛛.V‾= 0 as the continuity equation represents...
For general flow, ∂ρ / ∂t + V- ∙ (ρV ) = 0 ⋯ ①
If ρ = C
i. e. ρ ≠ ρ(x, y, z, t)
Hence equation ① is reduced to V ∙⃗V = 0 for incompressible flow.
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A flow field satisfying ⛛.V‾= 0 as the continuity equation represents...
Explanation:
The given equation is ⛛.V‾ = 0, where ⛛ denotes the divergence operator and V‾ represents the velocity vector. This equation is known as the continuity equation in fluid dynamics.
Continuity Equation:
The continuity equation is derived from the principle of conservation of mass and it states that the mass flow rate into a control volume must be equal to the mass flow rate out of the control volume. Mathematically, it can be expressed as:
⛛.V‾ = 0
where ⛛ is the divergence operator and V‾ is the velocity vector.
Interpretation of the Equation:
The divergence of a vector field represents the net flow of the field out of a small region. If the divergence is zero, it means that the net flow out of the region is zero, i.e., the flow entering the region is equal to the flow leaving the region.
Analysis of Options:
a) Steady Compressible Flow: In a steady flow, the velocity field does not change with time. However, the given equation does not specify anything about compressibility. Therefore, option (a) is not correct.
b) Incompressible Flow: An incompressible flow is characterized by constant density. In this case, the continuity equation simplifies to ⛛.V‾ = 0, which matches the given equation. Therefore, option (b) is correct.
c) Unsteady Incompressible Flow: In an unsteady flow, the velocity field changes with time. However, the given equation does not specify anything about compressibility. Therefore, option (c) is not correct.
d) Unsteady Compressible Flow: In an unsteady flow, the velocity field changes with time. Additionally, the given equation does not specify anything about compressibility. Therefore, option (d) is not correct.
Conclusion:
The given equation ⛛.V‾ = 0 represents an incompressible flow, where the velocity field satisfies the continuity equation. Therefore, option (b) is the correct answer.
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