Sec. 42.2 



POTENTIAL FLOW PATTERNS 

 TABLE 42.C— (Continued) 



37 



namics)," STG, 1904, Vol. 5, pp. 417-453. This 

 paper describes and illustrates Ahlborn's appa- 

 ratus and methods, in most of which the camera 

 (or observer) and the body were stationary while 

 the liquid moved past. As previously mentioned, 

 sawdust was employed as the suspended material 

 to produce the streamlines and path lines. The 

 objects tested in the first experiments were mostly 

 flat, bent, and curved plates, mounted singly and 

 in pairs. 



(2) "Die Wirbelbildung im Widerstandsmechanis- 

 mus des Wassers (The Phenomenon of Eddies and 

 Vortexes in the Mechanism of Resistance in 

 Water)," STG, 1905, Vol. 6, pp. 67-81. This paper 

 describes a continuation of Ahlborn's earlier 

 experiments, discussed and illustrated in the 

 reference preceding. It includes some stereophoto- 

 graphs of surface-flow phenomena, plus the 

 surface-flow and wave patterns about thick plank 

 models, models representing lapped butts (facing 

 forward and aft), lenticular planform and stream- 

 lined models, and a rather extensive series of 

 2-diml geometric models, with vertical axes, pro- 

 jecting through the surface. 



(3) "Die Wirkung der Schiffsschraube auf das 

 Wasser (The Working of the Ship Screw Propeller 

 in Water)," STG, 1905, Vol. 6, pp. 82-106. This 

 paper describes studies made by Ahlborn of the 

 3-diml flow about screw-propeller blades and 

 screw propellers themselves, at low speeds of 

 advance, including zero. Many of the illustrations 

 are stereophotographs in pairs. The data are 

 discussed at some length in Sec. 16.11 of Volume I. 



(4) "Die Widerstandsvorgange im Wasser an 

 Platten und Schiffskorpern. Die Entstehung der 

 Wellen (The Mechanism of Resistance in Water 

 as Affected by Plates and the Ship Hull. The 

 Production of Waves)," STG, 1909, Vol. 10, pp. 



370-436. This paper contains many photographs 

 and diagrams made by Ahlborn of streamUnes, 

 waves, separation zones, and eddies around flat 

 plates, some normal to the stream and some 

 yawed, some wholly submerged and some partly 

 immersed. In some cases the camera is stationary 

 with respect to the plate; in other cases it is 

 stationary with respect to the main body of 

 liquid. Between pages 408 and 409 of the reference 

 there are many photographs of thin, roughened 

 glass plates moving parallel to their own planes. 

 On pages 412 through 416 there are photographs 

 and diagrams of the liquid-particle motions in 

 gravity surface waves. Between pages 418 and 431 

 there are many photographs and diagrams of the 

 gravity-wave formation and the streamline flow 

 around small ship models, most of them with 

 blunt sterns. The latter group embodies photo- 

 graphs and diagrams of both streamlines and path 

 lines, depending upon whether the axes of refer- 

 ence are fixed in the model or in the overall body 

 of liquid. These photographs and diagrams war- 

 rant more study and analysis than have been 

 given to them in the past. 



Some two decades later, G. Fliigel pubUshed a 

 paper entitled "Ergebnisse aus dem Stromung- 

 sinstitut der Technischen Hochschule Danzig 

 (Results of Tests at the Flow Institute of the 

 Technical University, Danzig)" [STG, 1930, Vol. 

 31, pp. 87-113]. On pages 92 and following there 

 appear many excellent photographs of flow 

 patterns of liquid moving in channels and ducts 

 of varied and unusual shapes and around various 

 objects. O. G. Tietjens followed this with another 

 paper having the English title "Pictures of Flow 

 for Small and Medium Reynolds Numbers" 

 [Proc. 3rd Int. Congr. Appl. Mech., Stockholm, 



