d. The value of $ was obtained from the curve in Figure 8. Its 

 accuracy depends on how closely the theoretical curve approximates the 

 actual one. The exact shape of this curve can be confirmed only after 



a considerable amount of reliable data from the field becomes available. 



e. No approximation was involved in this step. 



f. The determination of the constant in equation (6-8) from the 

 experiment with an oscillating bottom is not quite accurate. The error 

 due to the value of this constant is not serious however, and can easily 

 be reduced as more information from field measurement is obtained. 



g. In order to determine the sediment rate in the direction of the 

 flow the concentration was multiplied by the average discharge in the bed 

 layer. This of course is only an approximation of the real mechanism. 

 The concentration in the layer actually remains constant in a statistical 

 sense only. The individual grains are continuously picked up and dropped 

 by the flow. Therefore the solid particles and the surrounding fluid are 

 subjected to random accelerations and decelerations. The effect of the 

 resulting inertia forces was assumed to be reflected by the value of the 

 empirical constant. However the accuracy of the method may be improved 

 considerably by refining the analysis of the force field in the bed layer. 



10. CONCLUSIONS 



Surface waves are responsible for the formation of an oscillatory 

 boundary layer near the ocean floor. For a certain range of values of 

 the wave parameters the laminar boundary layer becomes unstable. In this 

 case solid particles of bed material are brought to a state of incipient 

 equilibrium, primarily as the result of the instantaneous hydrodynamic 

 lift. The concentration of solid material, in a thin layer adjacent to 

 the bed (the bed layer) which at any instance is thus made free to move 

 can be determined by the method developed here . The rate of the transport 

 of such material in the direction of a secondary flow can be calculated 

 by multiplying this concentration with the average discharge due to the 

 secondary flow in the bed layer. The accuracy of the method should be 

 tested against actual field measurements. 



11. ACKNOWLEDGEMENTS 



The staff of the Hydraulic Laboratory of the University of California 

 and several students contributed in various capacities to the successful 

 completion of this study, and the writer is very grateful for this assist- 

 ance. He particularly expresses his gratitude to Professor Einstein for 

 the encouragement and the invaluable advice throughout the various phases 

 of the work. He also wishes to thank Professor Harder who gave freely of 

 his time to advise with the design and the assembling of the electronic 

 equipment used in the measurements. 



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