Hydrodynamics in a stirred tank in the transitional flow regime

Mendoza, F Jorge; Bañales, A. Lopes; Cid, Emmanuel; Xuereb, Catherine; Poux, Martine; Fletcher, David F.; Aubin, Joëlle

doi:10.1016/j.cherd.2017.12.011

Cited by 12 publications

(9 citation statements)

References 25 publications

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“…Similarly, Machado et al 30,31 also showed low Re associated to turbulent flow regimes for both axial and radial flow impeller types. Generally, lower ranges in Re have been associated with the turbulent flow transition as the impeller to tank diameter ( D / T ) ratio increases and with decreasing vessel size 29‐32 . This is consistent with the flow dynamics data presented in Part 1 of this work, where flow velocities scaled well across the rotational speeds investigated ( N = 75–120 rpm), suggesting the mean flow was fully developed and exhibits a turbulent regime…”

Section: Resultssupporting

confidence: 88%

Flow, suspension and mixing dynamics in DASGIP bioreactors, Part 2

2020

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This work aims to characterize the mixing and suspension dynamics occurring within two commercially available DASGIP bioreactor configurations, equipped with a twoblade paddle impeller with large impeller to tank diameter ratio, D/T = 0.97. Both continuous and intermittent agitation modes were employed to determine the impact that agitation strategy has upon mass transfer and microcarrier settling/suspension. This paper builds upon the flow dynamics data presented in Part 1 for a flat bottom DASGIP bioreactor and shows how intermittent agitation can break-up regions of slow mixing observed during continuous agitation, therefore substantially increasing the mixing efficiency of the system. Similarly, it was found that microcarrier characteristics might significantly affect the level of suspension when the impeller is in dwell status when intermittent agitation modes are used.

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Section: Resultssupporting

confidence: 88%

Flow, suspension and mixing dynamics in DASGIP bioreactors, Part 2

2020

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“…The observed effect of the RRF size on the numerical velocity magnitude profiles along the radial direction may be attributed to the following facts: 1) the use of a radial flow impeller in this study, since the highest velocity gradients exist in this direction; 2) the impeller region of influence (i.e. the circulating flow around the impeller) extends as the Re increases (Mendoza et al, 2018), and therefore, the radial extension of the RRF region must be extended as well.…”

Section: Rrf-region Size Effect On Local Velocitymentioning

confidence: 90%

“…Whilst the flow between the above two Re can be considered to be in the transitional flow regime. For Re around 100, the transient flow range is closer to the laminar regime, and therefore, it is common to conduct simulations in the laminar flow regime (Zalc et al, 2001;Gibbardo et al, 2006;Pakzad et al, 2013;Ramírez-Muñoz et al, 2016;Mendoza et al, 2018). Ramírez-Muñoz et al (2016) numerically studied the flow field induced by a standard Rushton turbine up to Reynolds number of 125 and evaluated the effect of the κ-κl-omega transition model introduced by Walters and Cokljat (2008).…”

Section: Numerical Considerationsmentioning

confidence: 99%

“…CFD techniques have become a useful tool to simulate laminar, transitional and turbulent flow in stirred tanks (Brucato et al, 2000;Van den Akker, 2006;Joshi et al, 2011a and2011b;Fathi Roudsari et al, 2012;Ramírez-Muñoz et al, 2016;Ramírez-Muñoz et al, 2017;Mendoza et al, 2018;Tamburini et al, 2018;Ameur, 2018;Márquez-Baños et al, 2019). An important aspect to consider when performing simulations of baffled stirred-tanks is the modeling of the impeller rotation.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the Rotating Reference Frame Size for Simulating a Mixing Straight-Blade Impeller in a Baffled Stirred Tank.

Concha-Gómez¹,

Ramírez-Muńoz²,

Márquez-Baños³

et al. 2018

Rev.Mex.Ing.Quim.

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“…As a CFD simulation framework, Fluent provides a variety of multi-motion reference system models, including a multireference frame (MRF) model, mixed plane model (MPM) and sliding mesh model (SMM) [28,29]. The basic idea of the MRF is to use the motion reference system to simulate the rotating area in which the stirrer is located and to use the static reference system to simulate the static area of the reactor that does not include any stirring blades.…”

Section: Boundary Conditions and Simulation Settingsmentioning

confidence: 99%

Comparative Study on the Power Consumption and Flow Field Characteristics of a Three-Blade Combined Agitator

et al. 2021

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The three-blade combined agitator consists of two propulsion blades of the same type (including planar propeller blades b, δ = 36.87°) and a curved blade (θ = 30°). Using numerical simulation methods, the power characteristics, flow field distribution, turbulence characteristics and dead zone percentage of two kinds of three-blade combined agitators (TBCAs) from laminar flow to turbulent flow in a mixing vessel were studied. Moreover, the torque measurement method was used to perform experimental verification. The results show that the predicted power curve is consistent with the experimental results. The fluid velocity near the propeller blades in the TBC-B type agitator (δ = 36.87°) is significantly high, and the maximum increase of the total velocity can reach 30.3%. The fluid flow velocity near the curved blades is increased, and the radial diffusion ability of the fluid at the bottom of the stirring vessel is enhanced. When mixing low-viscosity fluids, the TBC-B type agitator can increase the fluid velocity near the paddle area, with a maximum increase of 22.1%. The vertical combination of curved blades and planar propeller blades can effectively reduce the tangential velocity and increase the axial and radial velocities. When stirring high-viscosity fluids, the speed of the TBC-B type agitator in the near paddle area and far end of the blade is higher than that of the TBC-A type agitator. Under the same conditions, the TBC-B-type agitator exhibits superior fluid discharge performance and can be used in a wider range of viscosities. When Re = 44,910, the dead zone percentage of the TBC-A type agitator is 0.0216. The percentage of dead zones produced by the TBC-B-type agitator is smaller, and the mixing effect is superior to that of the TBC-A-type agitator.

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Hydrodynamics in a stirred tank in the transitional flow regime

Cited by 12 publications

References 25 publications

Flow, suspension and mixing dynamics in DASGIP bioreactors, Part 2

Flow, suspension and mixing dynamics in DASGIP bioreactors, Part 2

Effect of the Rotating Reference Frame Size for Simulating a Mixing Straight-Blade Impeller in a Baffled Stirred Tank.

Comparative Study on the Power Consumption and Flow Field Characteristics of a Three-Blade Combined Agitator

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