In this study, a micro-viscometer is developed for measuring shear-varying blood viscosity over a wide-ranging shear rate. The micro-viscometer consists of 10 microfluidic channel arrays, each of which has a different micro-channel width. The proposed design enables the retrieval of 10 different shear rates from a single flow rate, thereby enabling the measurement of shear-varying blood viscosity with a fixed flow rate condition. For this purpose, an optimal design that guarantees accurate viscosity measurement is selected from a parametric study. The functionality of the micro-viscometer is verified by both numerical and experimental studies. The proposed micro-viscometer shows 6.8% (numerical) and 5.3% (experimental) in relative error when compared to the result from a standard rotational viscometer. Moreover, a reliability test is performed by repeated measurement (N = 7), and the result shows 2.69 ± 2.19% for the mean relative error. Accurate viscosity measurements are performed on blood samples with variations in the hematocrit (35%, 45%, and 55%), which significantly influences blood viscosity. Since the blood viscosity correlated with various physical parameters of the blood, the micro-viscometer is anticipated to be a significant advancement for realization of blood on a chip.

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It is important to be able to predict the state of the boundary layer on a high-pressure turbine vane with incoming turbulence. The laminar-to-turbulent transition significantly changes the heat transfer on the blade, which impacts the turbine performance and durability assessment. In this study, an experimental cascade with a high-pressure turbine vane was simulated with large-eddy simulation (LES). To incorporate the impact of turbulence from the freestream on the boundary layer, appropriate turbulence data sets were generated in separate direct-numerical simulation and fed into the LES inlet. The state of the boundary layer is reasonably well predicted for the test condition of the turbulence intensity of Tu=4%. Streamwise vortical structures and spanwise two-dimensional waves are observed in the transitional boundary layer. Discrepancy for the case with the higher turbulence intensity Tu=6% is discussed with the focus on the need for more detailed information about the freestream disturbances.