Ill- 12 



Values of R as a function of ka for other fluid spheres are shown in Figure III-4. 

 Figure III- 5 shows the corresponding values of U . 



6 



R 3 



CURVE A - g = 1.0, h -. 0.8 

 CURVE B - g ^ ).0, h -. ].2 



CURVE C - g =2 0, h - 2.0 

 CURVE D - g =0.5, h - 0.5 



FIGURE III-4 THE REFLECTIVITY R AS A FUNCTION 



OF THE ACOUSTIC RADIUS Ka (AFTER 

 ANDERSON) 



The effect of scattering in other than the backward direction is illustrated in 

 Figure III- 6 for a number of spheres with g = 1. As might be expected, these 

 semi-transparent spheres scatter chiefly in the forward direction- -this is due 

 to the effect of refraction, which makes the spheres act as lenses. In general 

 these patterns possess lobes, the number of lobes increasing with increasing 

 ka and with decreasing h. It should be recalled that the quantity Rg does not 

 give directly the diffraction pattern due to a spherical obstacle; it represents 

 only the pressure amplitude in the spherically scattered wave and must be 

 combined with the incident plane wave to give the true diffraction pattern. 



artftur Sl.littleJitf. 



S-7001-0307 



