- 17 - 



Froude and Reynolds numbers with its prototype. In the scales 

 of oceanographic models the Reynolds niunbers of flow in the 

 model are often several orders of magnitude lower than corres- 

 ponding values in the prototype. 



In the Barataria Bay model two instances of deficient mixing 

 are potentially present due to stratification accompanying (1) 

 the density difference between the predominantly fresh drainage 

 of rainfall into the northwestern part of Barataria Bay via Bayou 

 St. Denis and Grand Bayou, and (2) the density difference between 

 the ambient water of the Barataria Bay-Lake Grande Ecaille system 

 and bleed water. Since there is at present no useful simultaneous 

 solution to the problem of combined Froude and Reynolds density 

 scales a choice was made in the first case in favor of the recip- 

 rocal Reynolds scale for increased realism of the circulation, 

 and in the second to abide with the unmodified Froude scale since 

 the injected volumes of bleed water exert a truly insignificant 

 effect on the circulation. 



The density difference between fresh water drainage and the 

 ambient density of Barataria Bay water is amply sufficient to 

 cause the fresh water to float on the surface of the ambient water 

 as a thin but very extensive sheet. This tendency exists in 

 nature to the same extent but it is overcome by the mixing proc- 

 esses associated with higher Reynolds numbers of flow, higher 

 eddy diffusivity, and mixing by wave action.. In nature the 

 several mixing processes carry the buoyant fresh water downward 



