Types of Fluid Flow – Compressibility and Rotation Which of the following statements about compressible flow, incompressible flow, and rotational flow is correct?
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AIn a compressible flow, the volume of the flowing liquid can change during the flow.
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BA flow in which the volume of the flowing liquid does not change is called incompressible flow.
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CWhen fluid particles rotate about their own axes while flowing, the flow is said to be rotational.
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Dall of the above
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Enone of the above
Answer
Correct Answer: all of the above
Explanation
Introduction:Classifying flows by compressibility and rotation is foundational in fluid mechanics. This question checks recognition of standard definitions and terminology.
Given Data / Assumptions:
- Terms: compressible, incompressible, rotational.
- Context: general fluid flow behavior, small to moderate pressure changes unless otherwise noted.
Concept / Approach:
Compressible flow involves appreciable density (and thus volume) changes with pressure or temperature variations. Incompressible flow assumes density remains effectively constant. Rotational flow implies nonzero vorticity where fluid elements experience spin about their own axes.
Step-by-Step Solution:
Step 1: Evaluate statement A. If density changes significantly, the fluid element volume changes; this characterizes compressible flow. The statement is acceptable in general terms.Step 2: Evaluate statement B. If the volume, equivalently the density, remains constant, the flow is modeled as incompressible; this is the standard textbook definition.Step 3: Evaluate statement C. Rotation of particles indicates finite vorticity; by definition this is rotational flow.Step 4: Since A, B, and C are all correct, the choice is “all of the above”.Verification / Alternative check:
Vorticity-based definitions and density-change criteria are consistent across common references for fluid kinematics and dynamics.
Why Other Options Are Wrong:
None of the above: Incorrect because each individual statement aligns with standard definitions.
Common Pitfalls:
Assuming liquids are always perfectly incompressible. Under very high pressures, even liquids can exhibit small compressibility; the definition here is about the model used, not the absolute impossibility of volume change.
Final Answer:
all of the above