Some Aspects of Very Large Offshore Structures 



NOMENCLATURE : 



a = cylinder radius 



c = spring constant of the anchor system 



d = water depth 



F = oscillating wave excited force 



F = drift force 

 ex 



F = reaction force of the anchor system 

 R 



F = amplitude of the horizontal wave excited force 

 xa 



F = amplitude of the vertical wave excited force 



Za 



g = acceleration due to gravity 



h = draught 



J = Bessel function of the first kind of order n 

 n 



J = derivative of J with respect to r 

 n, r n 



k = wave number 



K = modified Bessel function of the second kind of order n 

 n 



L. = lenght between perpendiculars 



PP 



M = oscillating wave excited moment 



p = pressure 



q = source strength 



Sp = spectral density of the waves 



Y = Weber's Bessel function of the second kind of order n 

 n 



Y = derivative of Y with respect to r 

 n, r n 



^ = wave length 



CO = circular frequency 



CO 



(^ = mean circular frequency in irregular waves 



p = fluid dens ty 



Y = Green's function 

 = velocity potential 



= wave function 



973 



