Sec. XI. 4 



SYMBOLS AND THEIR TITLES 



911 



velocity, for propeller tests, = (pAb. — e)/(0.5pFi) 



0- — Surface tension 



0-1 , 0-2 , etc. — Indexes of dynamic stability of 

 route 



ffcR — Cavitation index or number, critical 



2(sigma, large capital) — Sum, summation 



T(tau) — Shear, intensity of internal, in the 

 viscous flow of a liquid, proportional to (dU/dy); 

 shearing stress 



To — Shear intensity in a viscous liquid at a 

 solid-surface boundary 



<^(phi) — Angle, geometric pitch or heUx, of a 

 screw-propeller blade at any radius 



<f> — Angle of heel, Ust, or roll, reckoned about 

 the longitudinal ship axis 



<l> — Potential function such as a velocity 

 potential, where u = d(t>/dx, v = d<j)/dy, w = d<p/dz 



<i> — Coefficient, prismatic, = ¥/{LAx); alter- 

 native symbol Cp 



<t>v — Coefficient, prismatic, vertical; alternative 

 symbol Cpv 



^(psi) — Angle of yaw 

 }p — Current or stream function 

 1^0 — Radial stream function for a source 

 4'K — Radial stream function for a sink 

 ^s — Stream function for the flow around a 

 stream form 



w (omega) — Angular speed or velocity, generally 

 expressed as radians per unit time; alternative 

 sjnnbol n, generally expressed as revolutions per 

 unit time 



0(omega, capital) — Gravity potential, due to 

 the earth's gravity force. 



XI. 3 Abbreviations for Positions and Con- 

 ditions. 



C — Center 



E — Separation point on a body in a stream, 

 where the relative flow velocity becomes zero at 

 the body surface in the process of reversing direc- 

 tion 



K — Any point along the intersection of the 

 baseplane with the plane of sjonmetry 



N — Neutral or ambient-pressure point on a 

 body in a stream, where U = U„ and p = Pa, 



— Origin of coordinates 



Q — Stagnation point on a body in a stream, 

 where the relative flow velocity is zero and the 

 dynamic pressure equals the ram pressure q 



AP — After perpendicular, designed 



CA — Center of area 



CB — Center of buoyancy of a body or ship 



CE — Center of effort, as for the wind blowing 

 on a sail 



CF — Center of flotation; geometric or moment 

 center of the surface waterplane area A w 



CG — Center of gravity or center of mass of a 

 body or ship 



CM, CMt , M — Metacenter, for transverse in- 

 clination 



CMl , Ml — Metacenter, for longitudinal incli- 

 nation 



CP — Center of pressure of hydrodynamic forces 

 on a body 



CS — Static center; center of resultant of weight 

 W and buoyancy B 



CCF — Center of cross forces applied normal to 

 the direction of motion of the CG and normal to 

 the direction of lift 



CLA — Center of lateral area of the underwater 

 body, as projected on the plane of symmetry 



CLP — Center of lateral pressure; not neces- 

 sarily at the center of lateral area 



CWL — Construction waterline, as a position 

 only 



0-diml — Non-dimensional, as applied to phys- 

 ical expressions; also as apphed to flow having 

 characteristics variable in one dimension only 



2-diml — Two-dimensional, as applied to flow, 

 shape, and the like 



3-diml — Three-dimensional, as applied to flow, 

 shape, and the like 



DWL — Designed waterline, as a position only 



FP — Forward perpendicular, designed 



LE — Leading edge 



MP — -Mid perpendicular 



PP — Between perpendiculars; pivoting point 



SK — Sink, as a drain for radial flow 



SO — Source, as a source of radial flow 



TE— Trailing edge 



TP — Towing point or towed point 



WL — Waterline in general; free-surface water- 

 fine in any condition, undisturbed by waves; this 

 may or may not be at the DWL 



Sp.gr. — Specific gravity. 



XI. 4 Abbreviations for Physical Concepts 

 Having Scalar Dimensions. The superposed bar 

 or vinculum over the groups of letters in this 

 section indicate that they represent scalar quan- 

 tities, measurable in orthodox units. 



BD — Bilge-diagonal offset, at any station, 

 measured on the diagonal plane from the center- 

 line intersection to the hull surface 



