Hydraulic Jump Energy Loss
Calculate the specific energy dissipated in a hydraulic jump, ΔE = (y₂ − y₁)³ ÷ (4·y₁·y₂), from the upstream y₁ (supercritical) and downstream y₂ (subcritical) sequent depths. The hydraulic jump is one of the most efficient energy dissipators in hydraulics: intense turbulence in the transition converts kinetic energy to heat and sound, removing excess flow energy. This head loss ΔE is exactly what is sought downstream of spillways, gates and bottom outlets — water arrives with very high energy (able to scour the riverbed and undermine the structure), and the stilling basin induces the jump to 'burn' that energy in a controlled way. The higher the incoming Froude number, the greater the dissipated fraction — jumps with Fr > 9 dissipate up to 85%. Enter the upstream and downstream sequent depths.
Resultado
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Energia dissipada no ressalto hidráulico
O ressalto hidráulico é, na prática, um queimador de energia. A energia específica dissipada nele é ΔE = (y₂ − y₁)³ ÷ (4·y₁·y₂), calculada a partir das profundidades conjugadas de montante y₁ (rápida) e de jusante y₂ (lenta). A turbulência violenta na transição entre os regimes converte a energia cinética do escoamento rápido em calor, som e agitação, removendo o excesso de energia. É exatamente isso que se busca a jusante de vertedouros, comportas e descargas de fundo: a água chega com energia capaz de escavar o leito do rio em poucos minutos e comprometer toda a obra; a bacia de dissipação induz o ressalto para dissipar essa energia de forma controlada, dentro de uma estrutura blindada de concreto, devolvendo ao rio um escoamento manso e inofensivo. A eficiência impressiona: quanto maior o número de Froude incidente (maior a diferença entre y₁ e y₂), maior a fração dissipada — ressaltos com Fr > 9 chegam a eliminar 85% da energia. Esse é o princípio por trás das gigantescas bacias de dissipação que se veem ao pé dos vertedouros das grandes hidrelétricas, com seus blocos de impacto e soleiras terminais que estabilizam e reforçam o ressalto. Informe as profundidades conjugadas de montante e de jusante.
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