Motora and Koyama 



A t3rpical result for B= a and depth f = 2a is shown in Fig. 5 together with 

 the computed one. The base of Fig. 5 is a non-dimensionalized wave frequency 

 and the ordinate is the non-dimensionalized heaving force. The thick solid line 

 shows the heaving force of a semisubmerged circular cylinder of radius a/2. 



A remarkable decrease of the heaving force at a frequency approximately 

 equal to the theoretical ^^o will be recognized. 



Figure 6 is a typical oscillogram of the heaving force and the wave eleva- 

 tion as (^Vg)a = 0.124, 0.238, and 0.402. At (ajVg)a = 0.124, where the buoy- 

 ancy is greater than the inertia force, the heaving force is in phase with the 



Fig. 4 - Set-up of heaving force measurement 



^ 



0.5 



4EAVING FORCE FOR A CIRCULAR CYLINDER OF RADIUS 



% \N A FREE SURFACE 



J. 



1.0 1.5 2.0 



Fig. 5 - A typical result 



25 -jj^. 



3.0 



388 



