g = acceleration due to gravity; 

 V = kinematic fluid viscosity. 

 For convenience, a Table lists usual values of Pg, p, g, and v. 



Table. 



Values for material characteristics 

 used in calculations. 



Characteristic 



Values ! 



Sediment mass 



Quartz: 



5.14 slugs/ft^ (2.653 gm/cm^) 



density, pg 



Calcite: 



5.26 slugs/ft^ (2.711 gm/cm3) 



Fluid mass 



Freshwater: 



1.94 slugs/ft^ or 0.998 gm/cm^ 



density, p 





(20°C, 1 atmosphere pressure) 





Saltwater: 



1.99 slugs/ft 3 or 1.026 gm/cm^ 

 (35 •/.. salinity; 15°C. 

 1 atmosphere pressure) 



Acceleration due 

 to gravity, g 



Standard : 



32.2 ft (981 cm)/82 





ft2/e cm2/s 1 



Kinematic fluid 

 viscosity, V 



Freshuater: 



5°C: 1.64 X 10-5 0.0152 

 10*0: 1.41 X 10-5 0.0131 

 U'C: 1.23 X 10-5 0.0114 

 20''C: 1.08 X 10"5 0.0100 

 25''C: 0.96 x lO'S 0.0089 

 30*0: 0.86 x lO'S 0.0080 





Saltvater: 

 (35 v..) 



S'C: 1.69 X io"5 0.0157 

 lO'C: 1.45 X io"5 0.0135 

 15°C: 1.28 X 10"5 0.0119 

 20*C: 1.13 X 10"5 0.0105 

 25°C: 1.01 X 10-5 0.0094 



With these five values specified, sand motion initiation occurs at a pre- 

 dictable threshold near-bed fluid velocity, (Cw) , where 5, the horizontal 

 amplitude of the near-bed fluid excursion, is the single unknown. The condition 

 for motion with viscous effects dominant near the sand bed is 



^^ '^v 0.5 



(1) 



applicable for D < 0.07 centimeter and (5w)v < 1.15 feet (35 centimeters) per 

 second, according to empirical results. The condition for motion with viscous 

 effects negligible (due to a thoroughly mixed rather than laminar boundary 

 layer) is 



(50))^ = (8 Y'gD)0-5 



(2) 



