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用平均速度剖面法测量湍流边界层壁面摩擦速度的对比研究 被引量:11
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作者 王康俊 白建侠 +1 位作者 唐湛棋 姜楠 《实验力学》 CSCD 北大核心 2019年第2期209-216,共8页
基于不同雷诺数平板湍流边界层平均速度剖面,分别采用黏性底层拟合、对数律区拟合以及Spalding公式拟合算法计算了壁面摩擦速度,并对平均速度剖面进行无量纲化。通过比较无量纲化的平均速度剖面与理论规律曲线,验证了三种拟合计算方法... 基于不同雷诺数平板湍流边界层平均速度剖面,分别采用黏性底层拟合、对数律区拟合以及Spalding公式拟合算法计算了壁面摩擦速度,并对平均速度剖面进行无量纲化。通过比较无量纲化的平均速度剖面与理论规律曲线,验证了三种拟合计算方法的有效性。通过比较三种拟合算法所得的壁面摩擦速度与油膜干涉法直接测得的壁面摩擦速度之间的误差,并分析不同拟合算法误差形成的内在机制,验证了三种拟合算法计算结果的准确性与可靠性。结果表明Spalding拟合算法计算结果的准确性和可靠性都要优于其他两种拟合算法。 展开更多
关键词 湍流边界层 平均速度剖面 黏性底层 对数律区 Spalding公式 壁面摩擦速度
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SPECIES-AREA RELATIONSHIP FOR POWER-LAW SPECIES ABUNDANCE DISTRIBUTION
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作者 HARUYUKI IRIE KEI TOKITA 《International Journal of Biomathematics》 2012年第3期215-223,共9页
We studied the mathematical relations between species abundance distributions (SADs) and species-area relationships (SARs) and found that a power-law SAR can be generally derived from a power-law SAD without a spe... We studied the mathematical relations between species abundance distributions (SADs) and species-area relationships (SARs) and found that a power-law SAR can be generally derived from a power-law SAD without a special assumption such as the "canonical hypothesis". In the present analysis, an SAR-exponent is obtained as a function of an SAD-exponent for a finite number of species. We also studied the inverse problem, from SARs to SADs, and found that a power-SAD can be derived from a power-SAR under the condition that the functional form of the corresponding SAD is invariant for changes in the number of species. We also discuss general relationships among lognormal SADs, the broken-stick model (exponential SADs), linear SARs and logarithmic SARs. These results suggest the existence of a common mechanism for SADs and SARs, which could prove a useful tool for theoretical and experimental studies on biodiversity and species coexistence. 展开更多
关键词 Species-area relationship species abundance distribution power-law SAD.
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