Model Testing — Is Equal Velocity Ratio Dynamic or Kinematic Similarity? Consider the statement: “If the ratios of corresponding velocities at corresponding points are equal, then the model and prototype have dynamic similarity.” Choose the correct evaluation.

Introduction:
It is important to distinguish between kinematic and dynamic similarity in fluid modeling. Mislabeling these leads to wrong scaling laws and erroneous extrapolation from model to prototype.

Given Data / Assumptions:

• Velocity ratios at corresponding points are equal (with geometric similarity).
• No information given about forces or dimensionless numbers.

Concept / Approach:
Kinematic similarity means equality of the ratios of velocities and accelerations at corresponding points (and time correspondence), given geometric similarity. Dynamic similarity is stricter: it requires equality of force ratios, typically enforced by matching appropriate dimensionless groups (e.g., Reynolds, Froude, Weber, Mach) depending on dominant physics.

Step-by-Step Solution:
Check what is stated: equal velocity ratios ⇒ kinematic similarity.Dynamic similarity requires forces to scale; velocity equality alone does not ensure this.Therefore the statement is incorrect.

Verification / Alternative check:
Examples: Matching Reynolds number ensures dynamic similarity for viscous flows; matching Froude number ensures dynamic similarity where gravity waves dominate. Both go beyond mere velocity scaling.

Why Other Options Are Wrong:

• Correct: would conflate kinematic with dynamic similarity.

Common Pitfalls:
Assuming that if velocity fields look similar, then force fields do too; not necessarily true without matched dimensionless numbers.

Final Answer:
Incorrect