FLUIDODYNAMIC EVALUATION OF CIRCULAR AQUATIC TANK THROUGH THE COMPUTATIONAL FLUID DYNAMICS METHOD (CFD) FOR DIFFERENT HYDRAULIC CONFIGURATIONS

This research analyzed through the methodology of computational dynamics of fluids (CFD) the effect of tank design on water mixing in a circular tank with central bottom drainage. The analizes inclide three different depths:diameter proportion, specifically proportions 1: 3, 1: 5 and 1:10, and four configurations of water affluent piping: one with a horizontal radial pipe 10 cm above the water mirror, and three with a vertical pipe spaced 10 cm from the tank wall.

The study allowed to select the configuration that conjugated those water speeds that did not exceed the swimming speed of fish, and that is usually between 1 to 3 body lengths per second. Another requirement was that the generated speeds effectively allow the removal of solids by means of bottom velocities greater than 15 cm * s^-1.

The results obtained in the hydraulic analysis of the circular tanks showed that increasing their ratio between depth:diameter from 1: 3 to 1:10 a significant variation in the pattern of water circulation was generated. The speed magnitudes in the 3D reflected maximum values ​​of bottom velocities in the area near the drain for all three cases having ranges between 0 and 643 cm * s^-1.

The design with the best possibilities for the extraction of particles in the area near the drainage, and the one that presented greater stability, was for the tank with the ratio 1 to 10 for all its affluent configurations. On the other hand, the tank that presented greater variations in the three-dimensional velocity profiles for the four configurations evaluated was the tank with a 1 to 3 ratio, appreciating that this design tends to generate areas with zero turbulence and others with very high turbulence; reaching maximum speeds of 1090 ± 1600 cm * sec^-1, which is not ideal for particle evacuation.