Application of Richardson extrapolation method to the CFD simulation of vertical-axis wind turbines and analysis of the flow field

Meana-Fernández, Andrés; Oro, Jesús Manuel Fernández; Díaz, Katia María Argüelles; Vega, María Isabel Álvarez; Velarde-Suáréz, Sandra

doi:10.1080/19942060.2019.1596160

Cited by 29 publications

(27 citation statements)

References 49 publications

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“…In each case, the mesh refinement factor r ranged between

and

[ 74 ]. A safety factor

was used for the investigations [ 78 , 81 , 82 ]. The investigated criterion chosen was the mean Kolmogorov length, which occurs during one complete shaking period.…”

Section: Resultsmentioning

confidence: 99%

Improvement of HEK293 Cell Growth by Adapting Hydrodynamic Stress and Predicting Cell Aggregate Size Distribution

et al. 2023

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HEK293 is a widely used cell line in the fields of research and industry. It is assumed that these cells are sensitive to hydrodynamic stress. The aim of this research was to use particle image velocimetry validated computational fluid dynamics (CFD) to determine the hydrodynamic stress in both shake flasks, with and without baffles, and in stirred Minifors 2 bioreactors to evaluate its effect on the growth and aggregate size distribution of HEK293 suspension cells. The HEK FreeStyleTM 293-F cell line was cultivated in batch mode at different specific power inputs (from 63W/m3–451W/m3), whereby ≈60W/m3 corresponds to the upper limit, which is what has been typically described in published experiments. In addition to the specific growth rate and maximum viable cell density VCDmax, the cell size distribution over time and cluster size distribution were investigated. The VCDmax of 5.77±0.02e6cells/mL was reached at a specific power input of 233W/m3 and was 23.8% higher than the value obtained at 63W/m3 and 7.2% higher than the value obtained at 451W/m3. No significant change in the cell size distribution could be measured in the investigated range. It was shown that the cell cluster size distribution follows a strict geometric distribution whose free parameter p is linearly dependent on the mean Kolmogorov length scale. Based on the performed experiments, it has been shown that by using CFD-characterised bioreactors, the VCDmax can be increased and the cell aggregate rate can be precisely controlled.

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“…In each case, the mesh refinement factor r ranged between

and

[ 74 ]. A safety factor

was used for the investigations [ 78 , 81 , 82 ]. The investigated criterion chosen was the mean Kolmogorov length, which occurs during one complete shaking period.…”

Section: Resultsmentioning

confidence: 99%

Improvement of HEK293 Cell Growth by Adapting Hydrodynamic Stress and Predicting Cell Aggregate Size Distribution

et al. 2023

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“…First, meshes 1-3 were compared and second, meshes 2-4. For the analysis, a safety factor F s of 1.25 was used in each case and the meshes were chosen so that the mesh refinement ratio r was greater than 1.1 and was approximately 1.3 (Steffen et al, 1995;Roache, 1998;Meana-Fernández et al, 2019;Baker et al, 2020) (Eq. 10).…”

Section: Mesh Generation and Studymentioning

confidence: 99%

CFD modelling of a wave-mixed bioreactor with complex geometry and two degrees of freedom motion

et al. 2022

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Optimizing bioprocesses requires an in-depth understanding, from a bioengineering perspective, of the cultivation systems used. A bioengineering characterization is typically performed via experimental or numerical methods, which are particularly well-established for stirred bioreactors. For unstirred, non-rigid systems such as wave-mixed bioreactors, numerical methods prove to be problematic, as often only simplified geometries and motions can be assumed. In this work, a general approach for the numerical characterization of non-stirred cultivation systems is demonstrated using the CELL-tainer bioreactor with two degree of freedom motion as an example. In a first step, the motion is recorded via motion capturing, and a 3D model of the culture bag geometry is generated via 3D-scanning. Subsequently, the bioreactor is characterized with respect to mixing time, and oxygen transfer rate, as well as specific power input and temporal Kolmogorov length scale distribution. The results demonstrate that the CELL-tainer with two degrees of freedom outperforms classic wave-mixed bioreactors in terms of oxygen transport. In addition, it was shown that in the cell culture version of the CELL-tainer, the critical Kolmogorov length is not surpassed in any simulation.

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“…Richardson extrapolation is a method to attain a higher-order estimation of the continuum value from a series of lower-order discrete values [24] and is used as a computational tool for increasing the accuracy of numerical simulations. Moreover, this method can be used to validate the simulation results [25,26].…”

Section: Richardson's Extrapolationmentioning

confidence: 99%

A Modification of Offset Strip Fin Heatsink with High-Performance Cooling for IGBT Modules

2020

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For reliability and thermal management of power devices, the most frequently used technique is to employ heatsinks. In this work, a new configuration of offset strip fin heatsink based on using the concept of curvy fins and U-turn is proposed with the aim of improving the heat transfer performance. With this aim, a three-dimensional model of heatsink with Silicon Insulated-Gate Bipolar Transistors (IGBTs) and diodes, solder, Direct Bonded Copper (DBC) substrate, baseplate and thermal grease is developed. Richardson’s extrapolation is used for increasing the accuracy of the numerical simulations and to validate the simulations. To study the effectiveness of the new offset design, results are compared with conventional offset strip fin heatsink. Results show that in aspects of design of heatsinks (including heat transfer coefficient, maximum chip temperature and thermal resistance), the new introduced model has advantages compared to the conventional offset strip fin design. These enhancements are caused by the combination of the longer coolant passage in the heatsink associated with generation of disturbance and recirculation areas along the curvy fins, creation of centrifugal forces in the U-turn, and periodic breaking up boundary layers. Also, it is shown that due to narrower passage and back-and-forth route, the new introduced design can handle the hot spots better than conventional design.

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Application of Richardson extrapolation method to the CFD simulation of vertical-axis wind turbines and analysis of the flow field

Cited by 29 publications

References 49 publications

Improvement of HEK293 Cell Growth by Adapting Hydrodynamic Stress and Predicting Cell Aggregate Size Distribution

Improvement of HEK293 Cell Growth by Adapting Hydrodynamic Stress and Predicting Cell Aggregate Size Distribution

CFD modelling of a wave-mixed bioreactor with complex geometry and two degrees of freedom motion

A Modification of Offset Strip Fin Heatsink with High-Performance Cooling for IGBT Modules

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