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FLUID MECHANICS - CASE STUDY

    Introduction


An Attack Submarine in the Deep Sea
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A 1:10 scale model of an attack submarine is being tested in a water tunnel. The drag force ratio the submarine in the deep sea and the submarine model in the tunnel need to be estimated. The submarine cruises at 4 m/s in seawater (viscosity, μ = 1.2×10-3 N-s/m2 and density, ρ = 1,030 kg/m3). The fresh water in the tunnel is maintained at a temperature of 40 oC.

   
  Questions

 

What should the velocity of the model be in the tunnel? Determine the drag force ratio of the submarine prototype and model.

     
    Approach


 
  • Assume the submarine is far from the water surface.
  • Assume the compressibility of water is negligible.