The influence of reynolds number on the entry length and pressure drop for laminar pipe flow

Dombrowski, N.; Foumeny, E.A.; Ookawara, Shinichi; Riza, Ahmed

doi:10.1002/cjce.5450710320

Cited by 53 publications

(43 citation statements)

References 15 publications

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“…However, the entrance length must be sufficient to ensure fully developed flow before the streams reach the junction region. The empirical formula proposed by Dombrowski et al 46 Fig. 8, these two channel lengths provide almost identical simulation results: the averaged slug lengths are 65 lm and 64 lm; the corresponding periods are 218 lm and 220 lm.…”

Section: The Effect Of the Entrance Lengthssupporting

confidence: 60%

Computational investigations of the mixing performance inside liquid slugs generated by a microfluidic T-junction

Reddy

Kumar

et al. 2014

Biomicrofluidics

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Droplet-based microfluidics has gained extensive research interest as it overcomes several challenges confronted by conventional single-phase microfluidics. The mixing performance inside droplets/slugs is critical in many applications such as advanced material syntheses and in situ kinetic measurements. In order to understand the effects of operating conditions on the mixing performance inside liquid slugs generated by a microfluidic T-junction, we have adopted the volume of fluid method coupled with the species transport model to study and quantify the mixing efficiencies inside slugs. Our simulation results demonstrate that an efficient mixing process is achieved by the intimate collaboration of the twirling effect and the recirculating flow. Only if the reagents are distributed transversely by the twirling effect, the recirculating flow can bring in convection mechanism thus facilitating mixing. By comparing the mixing performance inside slugs at various operating conditions, we find that slug size plays the key role in influencing the mixing performance as it determines the amount of fluid to be distributed by the twirling effect. For the cases where short slugs are generated, the mixing process is governed by the fast convection mechanism because the twirling effect can distribute the fluid to the flow path of the recirculating flow effectively. For cases with long slugs, the mixing process is dominated by the slow diffusion mechanism since the twirling effect is insufficient to distribute the large amount of fluid. In addition, our results show that increasing the operating velocity has limited effects on improving the mixing performance. This study provides the insight of the mixing process and may benefit the design and operations of droplet-based microfluidics.

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Section: The Effect Of the Entrance Lengthssupporting

confidence: 60%

Computational investigations of the mixing performance inside liquid slugs generated by a microfluidic T-junction

Reddy

Kumar

et al. 2014

Biomicrofluidics

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“…The entrance length is the distance required for the centerline velocity to reach 99% of the fully developed velocity after a flow enters a narrow channel. The length is given by the following equation [19]:…”

Section: Influence Of Distance X Between Points Of Channel Confluencementioning

confidence: 99%

Design method for micromixers considering influence of channel confluence and bend on diffusion length

Aoki

Umei

Yoshida

et al. 2011

Chemical Engineering Journal

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a b s t r a c tIn micromixers, fluids deform through convection generated by variations in the shape of a channel, e.g., channel confluence and bend. This deformation enhances the mixing performance of the micromixer. In this study, we consider the effect of deformation on mixing performance in terms of a reduction in diffusion length, which is equivalent to the size of the fluid segments formed through fluid deformation. Based on improvements in the mixing rate through convection, we establish a design method that enables a micromixer to achieve a desired rapid mixing rate. For this purpose, we correlate the mixing performance of micromixers having various channel shapes and fluid velocities with the diffusion length; the equivalent mixing rate is obtained using computational fluid dynamics (CFD) simulations. The results of the CFD simulations reveal that the combination of fluid collision and channel bend after the development of the velocity profile of confluent flow is effective at enhancing the mixing rate. To establish a design method for a micromixer, we define and employ the energy dissipation rate based on the pressure drop profile in microchannels. The relationship between the segment size and the energy dissipation rate based on channel shape has been derived and integrated into the design method.

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“…The granular temperature profile is expected to become fully developed within the straight inlet channel before reaching the semicircular separator section. The following correlation for the entry length L e of a straight circular pipe (Dombrowski et al, 1993) was applied to a rectangular microchannel by substituting the hydraulic diameter for the pipe diameter (Kamholz et al, 1999;Ookawara et al, 2004d).…”

Section: Boundary Conditions and Numerical Schemesmentioning

confidence: 99%

Numerical study on development of particle concentration profiles in a curved microchannel

Ookawara

Street²,

Ogawa

2006

Chemical Engineering Science

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The influence of reynolds number on the entry length and pressure drop for laminar pipe flow

Cited by 53 publications

References 15 publications

Computational investigations of the mixing performance inside liquid slugs generated by a microfluidic T-junction

Computational investigations of the mixing performance inside liquid slugs generated by a microfluidic T-junction

Design method for micromixers considering influence of channel confluence and bend on diffusion length

Numerical study on development of particle concentration profiles in a curved microchannel

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