•16 



11M)R()I)VX A.MICS IN SHIP DESIGN 



Scr. 12.9 



tlie caw of asymmetric hcxlies of tin- kind shown 

 by Fig. 42.F. Nothing lias as yet been lieveloped 

 to take its place. For the time being it appears 

 useful to retain the enveloping stream surfaces, 

 such as those of diagrams 1 and 2 of Fig. 42. D, 

 along which the direction of flow is everywhere 

 tangent to the direction of those surfaces. They 

 are qualified, however, as surfaces for which the 

 tangent velocity — not necessarilj' the axial com- 

 ponent of that velocity — is constant around the 

 trace of the stream surface in any transverse 

 plane of the body. For any such section, these 

 traces form what are describetl in Sec. 1.4 and 

 illustrated in Fig. l.B of Volume I as isotachyls, 

 or contours of equal velocity. Unfortunately, they 

 do not define the flow completely because the 

 direction of the constant-velocity vector must 

 also be specified for every point around the 

 periphery. This can be done, at the expense of some 

 complication, by adding vectors alongside the 



contours representing the component in the 

 plane of the contour diagram, as is done in the 

 wake-survey diagrams of Sees. 11. G and 11.7 of 

 ^'^olume I and Sees. 60.0 and 60.7 of this volume. 



42.9 Flow, Velocity, and Pressure Around 

 Special Forms. It is certain that the toclmical 

 literature contains much more data on the flow 

 patterns and the velocity and pressure distribution 

 around bodies of special shape than are referenced 

 in this book and in others on hydrodynamics and 

 hydraulics. Moreover, it appears reasonable to 

 expect that, in the course of time, data in this 

 field which arc now da.ssificd will becume available 

 for general distribution. 



Among the special forms in this category arc 

 the planing surfaces on the bottoms of flying-boat 

 hulls and fast motorboats. A considerable amount 

 of experimental work on flow patterns under these 

 surfaces has been carried out by the National 

 Advisory Committee for Aeronautics and the 



Direction ond Moonilode of Uniform- Flow Velocity, Um^ 



Asymmetric Bod>^ whose Sections ore shown 

 here IS formed bvy J>locinQ Three Sources ond 

 One Sink in Q Uniform Streom Eoch Source 

 of Slrenqth m-l ot Stotion Zero is Offset 

 3 Lencjth Units or Stotion Intervals from the 

 Centerplone The Source m-3 is ol Sto. -5. 

 The Sink tn--5 is ot Sto 10. 



FISH-EYE VIEW 



cole for Stations 

 Alono the X-Akis 



TVie Numerals on the Diagram 

 and in the Table Represent the 

 Maqnitudes of the Tonqentiol 

 Velocities at the Points Indicoted. 

 Expressed as Multiples or Fractions 

 of the Uniform- Stream Velocity l^ 



8Urn 12 



Fiii. 42.F A»ruMK-riii(; Hmir Fhilmku hv I'l,\cino Tiiiikii: Souiiciis and One Sink in a Uniujiim Stkkam 



