similitude demands that Fr„ = Fr^, where m and p refer to model and prototype, 

 respectively. The Reynolds number is the ratio of the inertial forces to viscous forces 

 Re = ull V, where v is the fluid kinematic viscosity. So, in addition to geometric 

 similitude, complete similarity in damage requires Froude and Reynolds similitude or 



m m 



In stability models, Froude and geometric similitude are typically maintained leading to 

 the relationship between length and time scales of 



N, = N^=^, (4.4) 



where N-p N^ and N^ are the time, velocity, and length scales, respectively. Under 

 Froude similitude, in order to achieve Reynolds similitude, the following relationship 

 must be satisfied. 



^v = Nl' (4.5) 



where N^ is the viscosity scale ratio. Therefore, it is not practically possible to attain 

 both Reynolds and Froude similitude with the use of water in small-scale stability 

 experiments. Water is always used in stability models, yielding some Reynolds scale 

 effects. Thus the viscous forces are relatively stronger in the model than in the 

 prototype. 



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