Can We Achieve Similarity in Drag Testing for a Model Yacht?

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SUMMARY

The discussion centers on achieving similarity in drag testing for a model yacht, specifically a 5m yacht traveling at 10m/s and its 0.5m scale model. To ensure similarity, both the Reynolds number and Froude number must be equivalent for the yacht and the model. The viscosity in the tank must be adjusted accordingly, and increasing the flow speed in the tank by a factor of 10 is necessary to maintain similarity in the testing conditions.

PREREQUISITES
  • Understanding of Reynolds number and its significance in fluid dynamics.
  • Familiarity with Froude number and its application in model testing.
  • Basic knowledge of fluid density and viscosity concepts.
  • Experience with similitude principles in engineering and physics.
NEXT STEPS
  • Research the calculation and implications of Reynolds number in fluid dynamics.
  • Learn about Froude number and its role in model testing for naval architecture.
  • Explore methods to adjust viscosity in fluid testing environments.
  • Investigate case studies on drag testing for scale models in marine engineering.
USEFUL FOR

Naval architects, marine engineers, and students studying fluid dynamics or model testing methodologies will benefit from this discussion.

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Homework Statement



A yacht is of length 5m and travels at 10m/s. A scale model of length 0.5m is tested in a tank in order to predict drag on the yacht. Assuming that the fluid density and viscosity are the same for the yacht and model, can we obtain similarity?
What is our best value for viscosity in the tank?
What is the predicted drag ratio for drag on yacht to drag on model?

Homework Equations



Reynolds number, Froude number.

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The Attempt at a Solution



Not sure where to start with this one. Am i right in saying that both numbers need to be the same for both the yacht and model to obtain similarity?

Cheers.
 
Last edited:
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ok, so similarity can be obtained if the flow speed in the tank is increased by 10x?
 

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