We present an experimental and numerical study of the turbulent boundary layer at \(1200< Re_{\theta} <3400\). We propose a combined approach that involves the use of a multi-hole pitot probe, hot-wire anemometry and direct numerical simulations, that allows to characterise the isotropy and the energy dissipation scalings of the flow in the outer layer, in the range \(0.4< y/\delta <0.75\), with y the vertical coordinate and \(\delta\) the boundary layer thickness. We confirm previous results from the literature that show that for low values of \(Re_{\theta}\) (in our case \(Re_{\theta} <2500\)), on the outer layer the dissipation constant \(C_\varepsilon\) is Reynolds number dependent, following a \(Re_\lambda ^{-1}\) law. This dependency seems to be robust, as the value of \(C_\varepsilon\) collapses for previously reported direct numerical simulations and experiments with different incoming velocities. We also show that, while large scales of the flow are strongly anisotropic on the outer layer, the turbulence energy dissipation rate and the dissipation constant can still be characterised assuming local isotropy and homogeneity.

我们对\（1200 <Re _ {\ theta} <3400 \）处的湍流边界层进行了实验和数值研究。我们提出了一种组合方法，其中涉及使用多孔皮托管探头，热线风速仪和直接数值模拟，该方法可以表征外层中流的各向同性和能量耗散标度，范围为\（ 0.4 <y / \ delta <0.75 \），其中y为垂直坐标，\（\ delta \）为边界层厚度。我们从文献中证实了先前的结果，这些结果表明，对于\（Re _ {\ theta} \）的低值（在我们的情况下为\（Re _ {\ theta} <2500 \）），在外层上的耗散常数\（C_ \ varepsilon \）遵循\（Re_ \ lambda ^ {-1} \）律，与雷诺数有关。这种依赖性似乎很可靠，因为对于以前报告的直接数值模拟和具有不同传入速度的实验，\（C_ \ varepsilon \）的值会崩溃。我们还表明，尽管在外层上大尺度的流动是强烈各向异性的，但假设局部各向同性和均质性，湍流能量耗散率和耗散常数仍然可以表征。