000202378 001__ 202378
000202378 005__ 20180317094100.0
000202378 0247_ $$2doi$$a10.1007/s10404-013-1321-7
000202378 022__ $$a1613-4982
000202378 02470 $$2ISI$$a000341097400012
000202378 037__ $$aARTICLE
000202378 245__ $$aSudden expansions in circular microchannels: flow dynamics and pressure drop
000202378 260__ $$aHeidelberg$$bSpringer Heidelberg$$c2014
000202378 269__ $$a2014
000202378 300__ $$a12
000202378 336__ $$aJournal Articles
000202378 520__ $$aMicro particle shadow velocimetry is used to study the flow of water through microcircular sudden expansions of ratios e = 1.51 and e = 1.96 for inlet Reynolds numbers Re (d) < 120. Such flows give rise to annular vortices, trapped downstream of the expansions. The dependency of the vortex length on the Reynolds number Re (d) and the expansion ratio e is experimentally investigated in this study. Additionally, the shape of the axisymmetric annular vortex is quantified based on the visualization results. These measurements favorably follow the trends reported for larger scales in the literature. Redevelopment of the confined jet to the fully developed Poiseuille flow downstream of the expansion is also studied quantitatively. Furthermore, the experimentally resolved velocities are used to calculate high resolution static pressure gradient distributions along the channel walls. These measurements are then integrated into the axisymmetric momentum and energy balance equations, for the flow downstream of the expansion, to obtain the irreversible pressure drop in this geometry. As expected, the measured pressure drop coefficients for the range of Reynolds numbers studied here do not match the predictions of the available empirical correlations, which are commonly based turbulent flow studies. However, these results are in excellent agreement with previous numerical calculations. The pressure drop coefficient is found to strongly depend on the inlet Reynolds number for Re (d) < 50. Although no length-scale effect is observed for the range of channel diameters studied here, for Reynolds numbers Re (d) < 50, which are typical in microchannel applications, complex nonlinear trends in the flow dynamics and pressure drop measurements are discovered and discussed in this work.
000202378 6531_ $$aMicrofluidics
000202378 6531_ $$aCircular microchannel
000202378 6531_ $$aSingular pressure drop
000202378 6531_ $$aMinor pressure loss
000202378 6531_ $$aVelocimetry
000202378 6531_ $$amu lPSV
000202378 700__ $$0243079$$aKhodaparast, Sepideh$$g177360
000202378 700__ $$aBorhani, Navid
000202378 700__ $$0240577$$aThome, John Richard$$g108776
000202378 773__ $$j17$$k3$$q561-572$$tMicrofluidics And Nanofluidics
000202378 909CO $$ooai:infoscience.tind.io:202378$$particle$$pSTI
000202378 909C0 $$0252128$$pLTCM$$xU10312
000202378 917Z8 $$x206908
000202378 937__ $$aEPFL-ARTICLE-202378
000202378 973__ $$aEPFL$$rREVIEWED$$sPUBLISHED
000202378 980__ $$aARTICLE