Basin-Scale Internal Waves
Experiments/Research performed by Rafael Bueno
August 2017 - actual
​
This project is a group of studies investigating the hydrodynamic of basin-scale internal waves and its energy cascade that produces high-frequency internal waves in stratified basins, such as lakes and reservoirs. Frequently the wind that blows at lake surface transfers energy to the system. More than 80% of the wind energy is responsible to excite large-period internal seiches. Studies show that these waves are responsible to large scale motion, in which up to 40% of hypolimnetic volume may be exchanged after its passage. The dynamic of basin-scale internal wave affects strongly the water quality of these ecosystems. Many recent studies have pointed out that water quality if effected strongly by the internal wave activity, which influence nutrients, microorganisms, and chemical compounds fluxes.
New technologies have provided a better understanding of internal waves patterns in basins, revealing their strong influence on the system dynamic. The spectral analysis and the improvement on water temperature measurement have proved to be an useful to improve the detection of internal waves in lakes. A phenomenon that initially appeared to be excited just in some rare cases, actually is frequently in lakes and reservoirs of different sizes and shapes.
In the example beside, the upper figure shows apparently a smooth system, as if it has no dynamic at all, similar to a puddle. However, the instability caused by wind-driven current and the stratified system favor the occurrence of basin-scale internal waves, in which the oscillation occurs near the thermocline. These baroclinic effects play a major role in the system, and control the hydrodynamic of the stratified basins.
In addition, depending on the stratification and the basin topography, higher vertical modes may be excited in different depths of the system. The explanation of why different modes is excited is out of the scope of this analyses.
This project provides an analyses of the importance of the shear velocity as a source of turbulent kinetic energy available for mixing during an internal wave event considering different instability conditions. This analysis provide a classification of internal wave as a function of Wedderburn number and a detailed analyses of internal wave resonance due to wind variation.
​
​
Findings:
​
x
Products :
Bueno, R.; Hoeltgebaum, L.; Colombo, G.; Mannich, M.; Bleninger, T. - Análise experimental da formação de ondas internas gravitacionais a partir de correntes de gravidade. II Encontro Sul Brasileiro de Engenharia Ambiental e Sanitária, Foz do Iguaçu-PR, Brazil, 2018.
​
Hoeltgebaum, L.; Colombo, G.; Bueno, R.; Bleninger, T.; Mannich, M. - Análise experimental da estratificação causada por correntes de gravidade sobre fundo liso e rugoso. II Encontro Sul Brasileiro de Engenharia Ambiental e Sanitária, Foz do Iguaçu-PR, Brazil, 2018.
​
Bueno, R.; Marcon, L.; Wosiacki, L.; Romero, M.; Bleninger, T.; Mannich, M. - Correntes de gravidade e de intrusão produzidas pelo experimento lock-exchange (Gravity currents produced by lock-exchange and intrusion). XXII Simpósio Brasileira de Recursos Hídricos, Florianópolis-SC, Brazil, 2017.