Testing model yachts for drag.

In summary, the conversation discusses the use of a scale model in a tank to predict drag on a yacht of length 5m traveling at 10m/s. The question is whether similarity can be obtained if the fluid density and viscosity are the same for both the yacht and model. The relevant dimensionless parameters are the Reynolds number and Froude number. The conclusion is that similarity can be obtained if the flow speed in the tank is increased by 10x.
  • #1
meb09JW
23
0

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.

04a9a22ed9954b1575f65bbf1709ac18.png


79105b25af630de97018f428e2f93dad.png


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:
Physics news on Phys.org
  • #3
ok, so similarity can be obtained if the flow speed in the tank is increased by 10x?
 

Related to Testing model yachts for drag.

1. What is drag and why is it important to test for it in model yachts?

Drag is the force that acts against the motion of an object through a fluid, in this case water. It is important to test for drag in model yachts because it can significantly affect their speed and performance in the water. By minimizing drag, the yacht can move faster and more efficiently through the water.

2. How is drag measured in model yachts?

Drag is typically measured using a force sensor or load cell attached to the yacht. The yacht is then pulled through the water at a constant speed and the force required to maintain that speed is recorded. This force measurement is then used to calculate the drag coefficient, which is a measure of the resistance of the yacht to motion through the water.

3. What factors can affect the drag of a model yacht?

The shape and design of the yacht, as well as its size and weight, can all affect the drag. A streamlined design with smooth surfaces will generally have lower drag compared to a yacht with complex shapes and rough surfaces. The water conditions, such as waves and currents, can also impact the drag of a model yacht.

4. How can drag be reduced in model yachts?

There are several methods for reducing drag in model yachts. One way is to optimize the design and shape of the yacht for minimal resistance in the water. This can be achieved through wind tunnel testing or computer simulations. Another approach is to use materials with lower friction, such as smooth and lightweight materials. Additionally, keeping the yacht clean and free of any debris or algae can also help reduce drag.

5. Can drag testing in model yachts be applied to larger vessels?

Yes, the principles and methods used for drag testing in model yachts can also be applied to larger vessels. However, the scale and complexity of larger vessels may require more advanced techniques and equipment for accurate drag measurements. Wind tunnel testing, computational fluid dynamics, and towing tanks are commonly used for drag testing in larger vessels.

Similar threads

Range of Reynold's numbers (Drag Lab)
    • Engineering and Comp Sci Homework Help
Replies
9
Views
2K
Fluid dynamics: Reynolds Number, Drag Constant
    • Engineering and Comp Sci Homework Help
Replies
2
Views
2K
Advanced Hydrodynamic Problem - University level
    • Engineering and Comp Sci Homework Help
2
Replies
49
Views
3K
Fluid Dynamics-Drag Force Problem.
    • Engineering and Comp Sci Homework Help
Replies
8
Views
17K
How Does Drag Affect Airplane Dynamics in a Four-Dimensional Universe?
    • Sci-Fi Writing and World Building
Replies
18
Views
2K
Drag Coefficient and Reynolds Number Related to free fall
    • Engineering and Comp Sci Homework Help
Replies
4
Views
6K
How to replicate a realistic Reynolds number for an airfoil
    • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
Brownian Ratchet (exercise framed by Feynman's Lectures, l. 46)
    • Introductory Physics Homework Help
Replies
32
Views
1K
Fluid mechanics- Dimensional analysis
    • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
Similitude, Dimensional analysis for fluid mech.
    • Engineering and Comp Sci Homework Help
Replies
1
Views
3K

Hot Threads

Recent Insights

Back
Top