The equations for double-mean, form-induced and spatially averaged turbulent energy budgets are employed to analyse data from direct numerical simulations of turbulent open-channel flows over transitionally rough mobile beds with intermediate flow submergence. Two scenarios were considered related to (i) near-critical bed condition, and (ii) fully mobile bed condition. The bed was composed of a layer of mobile spherical particles moving on the top of one layer of fixed particles of the same size. Data analysis showed the leading energy exchanges between double-mean, form-induced, turbulent flow field contributions as well as particle motions. Above the fixed particles tops, the turbulent flow receives kinetic energy directly from the mean flow as well as from moving bed particles, which in turn also receive energy from the mean flow. For near-critical bed condition, particle aggregations enhanced mean-flow heterogeneity, strengthened turbulent stresses and their effects on the flow, while at increased bed-mobility, energy transport mechanisms became weaker and conversions induced by viscous stresses and pressure became stronger.

中文翻译：

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移动颗粒床流动中的双平均动能预算：来自 DNS 数据分析的见解

双均值、形状诱导和空间平均湍流能量收支的方程用于分析来自具有中间流淹没的过渡粗糙移动床上的湍流明渠流的直接数值模拟的数据。考虑了与 (i) 接近临界床条件和 (ii) 完全移动床条件相关的两种情况。该床由一层移动的球形颗粒组成，它们在一层相同尺寸的固定颗粒的顶部移动。数据分析表明，双均值、形式诱导、湍流流场贡献以及粒子运动之间的主要能量交换。在固定颗粒顶部上方，湍流直接从平均流和移动床颗粒接收动能，而移动床颗粒又从平均流接收能量。