Identify the incorrect statement about radial flow Which of the following statements is NOT correct for radial flow fields (e.g., flow toward or away from a centerline)?
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APressure and velocity may change with distance from the central axis
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BVelocity of flow is primarily in a radial direction
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CFlow may occur either radially inward or radially outward
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DFlow is one-dimensional with streamlines parallel
Answer
Correct Answer: Flow is one-dimensional with streamlines parallel
Explanation
Introduction / Context:Radial flow occurs in pumps, wells, and around bluff bodies. It differs from rectilinear flow because streamlines converge toward or diverge from a point/axis, altering geometry and kinematics.
Given Data / Assumptions:
- Axisymmetric, inviscid-style reasoning for basic identification.
- Flow direction is predominantly radial.
Concept / Approach:In radial flow, streamlines are not parallel; they either converge or diverge, causing pressure and velocity to vary with radius. Thus, any statement implying “streamlines parallel” is inconsistent with the very definition of radial motion.
Step-by-Step Solution:
Check (a): variation with radius r is expected → correct.Check (b): direction predominantly radial → correct.Check (c): both inward and outward patterns exist → correct.Check (d): “streamlines parallel” contradicts radial geometry → incorrect statement.Verification / Alternative check:Potential-flow solution for a source/sink has V_r ∝ 1/r and streamlines radiating from/into the origin; clearly not parallel.
Why Other Options Are Wrong:Options (a)–(c) accurately describe radial flow behavior.
Common Pitfalls:Confusing “one-dimensional” with “parallel streamlines”; even simplified 1-D radial models do not imply parallel lines.
Final Answer:Flow is one-dimensional with streamlines parallel