An underwater study of a porpoise is to be performed by using a 1:10 scale model. A porpoise swimming at 10 m/s and making one swimming motion each second is to be simulated. What speed could be used in the water channel, and for that speed, how many swimming motions per second should be used?

Question

Accepted Answer

[latex] Re_m=Re_p . ∴ \frac{V_m\ell _m}{ u _m} =\frac{V_p\ell _p}{ u _p} . ∴ {V_m} ={V_p} {\frac{\ell _p}{\ell _m} } =10 imes 10=100 m/s [/latex] .

This is too large for a water channel. Undoubtedly this is a high-Re flow. Select a speed of [latex] \underline{5 m/s}[/latex] . For this speed,

[latex] Re_m =\frac{5 imes 0.1}{1 imes 10^{-6}} =5 imes 10^5[/latex] ,

where we used [latex] \ell _m = 0.1 (\ell _ p [/latex]= 1 m, i.e., the dia. of the porpoise).

[latex] ω_m =ω_p (V_m /V_p )(\ell _p /\ell _m) =1×(5/10)×10 = \underline{5 motions/second}[/latex] .

Question 6.68: An underwater study of a porpoise is to be performed by usin...

This Question has been Answered.

Already have an account?

Login

Related Answered Questions