Numerical simulation of density current effects on turbulence characteristics of flow in bottom outlets

Water and soil conservation activities cannot limit sediment production on watersheds, completely and it seems that the only practical way to remove the sediments from the reservoir is to flush it out by bottom outlets. Because of the importance of turbulence energy in air entrainment to flow and cavitation occurrence, in this paper numerical simulation of sediment transport through the bottom outlet of the dam is performed. For this purpose, first, the air-water mixture in bottom outlet is simulated and the results are compared with experimental measurements. Then, a three phase flow with two sediment concentrations of 300 and 500 gr/lit are simulated to investigate the effect of sediment concentration on flow turbulence and its energy. The results show that the turbulence energy is negligible in flow with high sediment concentration in comparison with clear water and only affects on the flow surface and near the gate. Adding sediment particles to the flow leads to reduce the turbulence intensity of flow through bottom outlet tunnel, so that, increasing its concentration to 300gr/lit reduces the maximum of turbulence energy about 50%.Water and soil conservation activities cannot limit sediment production on watersheds, completely and it seems that the only practical way to remove the sediments from the reservoir is to flush it out by bottom outlets. Because of the importance of turbulence energy in air entrainment to flow and cavitation occurrence, in this paper numerical simulation of sediment transport through the bottom outlet of the dam is performed. For this purpose, first, the air-water mixture in bottom outlet is simulated and the results are compared with experimental measurements. Then, a three phase flow with two sediment concentrations of 300 and 500 gr/lit are simulated to investigate the effect of sediment concentration on flow turbulence and its energy. The results show that the turbulence energy is negligible in flow with high sediment concentration in comparison with clear water and only affects on the flow surface and near the gate. Adding sediment particles to the flow leads to reduce the turbulence intensity of flow through bottom outlet tunnel, so that, increasing its concentration to 300gr/lit reduces the maximum of turbulence energy about 50%.Water and soil conservation activities cannot limit sediment production on watersheds, completely and it seems that the only practical way to remove the sediments from the reservoir is to flush it out by bottom outlets. Because of the importance of turbulence energy in air entrainment to flow and cavitation occurrence, in this paper numerical simulation of sediment transport through the bottom outlet of the dam is performed. For this purpose, first, the air-water mixture in bottom outlet is simulated and the results are compared with experimental measurements. Then, a three phase flow with two sediment concentrations of 300 and 500 gr/lit are simulated to investigate the effect of sediment concentration on flow turbulence and its energy. The results show that the turbulence energy is negligible in flow with high sediment concentration in comparison with clear water and only affects on the flow surface and near the gate. Adding sediment particles to the flow leads to reduce the turbulence intensity of flow through bottom outlet tunnel, so that, increasing its concentration to 300gr/lit reduces the maximum of turbulence energy about 50%.Water and soil conservation activities cannot limit sediment production on watersheds, completely and it seems that the only practical way to remove the sediments from the reservoir is to flush it out by bottom outlets. Because of the importance of turbulence energy in air entrainment to flow and cavitation occurrence, in this paper numerical simulation of sediment transport through the bottom outlet of the dam is performed. For this purpose, first, the air-water mixture in bottom outlet is simulated and the results are compared with experimental measurements. Then, a three phase flow with two sediment concentrations of 300 and 500 gr/lit are simulated to investigate the effect of sediment concentration on flow turbulence and its energy. The results show that the turbulence energy is negligible in flow with high sediment concentration in comparison with clear water and only affects on the flow surface and near the gate. Adding sediment particles to the flow leads to reduce the turbulence intensity of flow through bottom outlet tunnel, so that, increasing its concentration to 300gr/lit reduces the maximum of turbulence energy about 50%.