HYDRODYNAMIC FORCES 



113 



Cross-Sectionil Forms 



Direction of Motion 

 Axis of Rotation 



*^ Sol 



CT 



^•\^^l^y '^^ 



Za 



c3 



2a- 



\m 



i=> 



T=' 



-r = 2.6 



T = 1.8 



-^ = 1.5 



Hydrodynamic Mass 

 per Unit Length 



121 

 = V2 siluafe 



0,25 nga^ 



15) 



: 0.755 TTga* 



/■5/ 



til 

 0.»9 Tjga^ 



nertia Coefficient 

 m" 



C = 



m"circle 



0.75 



0.25 



0.75 



0.83 



0.89 



^ Inga^ 



/«/ 



= 2 



Regular 

 Octagon 



161 



1.35 7rea2 



^ 2/rea^ 



/«/ 



12/ 



■ O.lGnga^ 



121 



O.iil nga'^ 



121 



O.fil 77 oa^ 





^ 1 



^ 1.35 



0.76 



0.67 



0.61 



0.85 



Hydrodynamic Monent 



of Inertia 



per Unit Lengtii 



HI 



= 0.\\lngcL* 



Inertia Coefficient 

 for Rotation 



1^1 



= 0.059 7r£»a< 



[11 



^ 0.055 n-e a" 



0.936 



0.47 



0.44 



Fig. 5 Tabulation of hydrodynamic masses, hydrodynamic moments of inertia, and inertia coefficients as calculated by [1] Lamb, 

 [2] Lewis, [3] Proudman, |4| Weinblum, [5| Wendel, [6| determined experimentally (electrical analog) by Koch (from Wendel, 



1950) 



added-mass coefficient was expressed as a function of a 

 nondimensional frequency parameter u-r/irg. The re- j^^ ^ 

 suits can be conveniently interpreted as a correction 

 coefficient* 



added mass of a body floating on water surface 

 added mass of a !iody deeply submerged 



(19) 



8 This correction coefficient w;is first used in ship-motion anal- to inertia of a submerged body in three directions, he used the 

 ysis by B. V. Korvin-Kroukovsky (1955c). Having assigned notation A-, for the added mass correction of a liody floating on the 

 (following Lamb J the notation A-|,2,3 to the coefficient of accession water surface. 



