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CFD modeling of droplet generation process for medical applications using the electrostatic impulse method

Cendrowski Piotr, Kramek-Romanowska Katarzyna, Lewińska Dorota, Grzeczkowicz Marcin, Korycka Paulina, Krzysztoforski Jan

Chemical and Process Engineering

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2022

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Vol. 43, nr 3

331-–355

EN

The electrostatic impulse method is an established method for producing microbeads or capsules. Such particles have found application in biomedical engineering and biotechnology. The geometric properties of the droplets – constituting precursors of microbeads and capsules – can be precisely controlled by adjusting the geometry of the nozzle system, the physical properties and the flow rate of the fluids involved, as well as the parameters of the electrostatic impulse. In this work, a method of mathematical modeling of the droplet generation process using the electrostatic impulse method in a single nozzle system is presented. The developed mathematical model is an extension of the standard Volume of Fluid (VOF) model by addition of the effect of the electric field on the fluid flow. The model was implemented into the OpenFOAM toolkit for computational fluid dynamics (CFD). The performed CFD simulation results showed good agreement with experimental data. As a result, the influence of all process parameters on the droplet generation process was studied. The most significant change in droplet generation was caused by changing the electrostatic impulse strength. The presented modeling method can be used for optimization of process design and for studying the mechanisms of droplet generation. It can be extended to describe multi nozzle systems used for one-step microcapsule production.

2

Implementation of turbulence damping in the OpenFOAM multiphase flow solver interFoam

Polansky Jiri, Schmelter Sonja

Archives of Thermodynamics

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2022

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Vol. 43, no 1

21--43

EN

In the presented work Egorov’s approach (adding a source term to the ω-equation in the k-ω model, which mimics the damping of turbulence close to a solid wall) was implemented in on the subclass of shear stress transport models. Hence, turbulence damping is available for all shear stress transport type models, including hybrid models that are based on the ω-equation. It is shown that turbulence damping improves the prediction of the axial velocity profile not only for Reynolds-averaged Navier–Stokes simulation but also for detached eddy simulation and delayed detached eddy simulation models. Furthermore, it leads to a more realistic estimation of the pressure drop and, hence, to a more correct prediction of the liquid level. In this paper, simulation results for four different turbulence models are presented and validated by comparison with experimental data. Furthermore, the influence of the magnitude of the damping factor on the pressure drop in the channel is investigated for a variety of different gas-to-liquid flow rate ratios. These investigations show that higher gas-to-liquid flow rate ratios require higher damping factors to correctly predict the pressure drop. In the end, advice is formulated on how an appropriate damping factor can be determined for a specific test case.

3

Numerical Modeling of Compound Channels for Determining Kinetic Energy and Momentum Correction Coefficients Using the OpenFOAM Software

Mehranfar Nariman, Ghanbari-Adivi Elham

Archives of Hydro-Engineering and Environmental Mechanics

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2022

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Vol. 69, nr 1

27--43

EN

The non-uniformity of the flow velocity distribution in each section of compound channels and in the main channel-floodplain interface area causes errors in estimating water surface profile, flood routing, pollution transfer, and so on. To reduce the impacts of non-uniformity on the exact calculation of kinetic energy and momentum, α and β correction coefficients are used, respectively. However, the determination method of these coefficients is a challenging issue in river engineering. This study used the OpenFOAM Software to determine these coefficients numerically for two laboratory models of compound open channels of which the data are available, using the single-phase pimpleFoam solver to do modeling in the mentioned software and the k-ωSST turbulence model to calculate the flow characteristics. Based on the results, the highest difference (13%) between the results estimated by the software and those obtained from the lab experiments was seen in the low flow depth where the flow left the main channel and entered the floodplain of a very shallow depth, possibly due to the grid generation of this area. This difference decreased as the flow depth increased, and its average was 6.65% for α coefficient and 2.32% for β coefficient in all cases, which means the results of numerical modeling and the experimental data conformed well, and the OpenFOAM software can be successfully used in flow modeling and analyzing flow characteristics in compound channels.

4

Numerical simulations of the flows past rotating geometries

Simon Jakub, Stankiewicz Witold

Vibrations in Physical Systems

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2020

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Vol. 31, nr 3

art. no. 2020318

EN

In the present paper the numerical approach for the modeling of the flow past rotating geometries is presented. Practical methods for two cases are described: the one where whole domain is moving with uniform angular velocity, where the rotation might be included in the governing equations only (in the terms related to Coriolis and centrifugal forces), and the one where part of the domain is rotating, whereas another one is stationary. The second case is illustrated by examples describing the steady and transient flow around a rotating propeller and by a centrifugal pump. Simulations are performed using OpenFOAM CFD solver, with the models covering flow rotation: MRF (multiple reference frame) and AMI (arbitrary mesh interface).

5

Numerical methodology for analyzing the performance of a solarupdraft tower in various environmental conditions

Brenk Arkadiusz, Malecha Ziemowit, Tomkow Lukasz

Journal of Power Technologies

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2020

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Vol. 100, nr 2

144--151

EN

This paper investigates a simplified and fast numerical model of a solar updraft tower. The model applies a novel approach to the calculation of heat transfer from the outside environment to a collector in the tower. Complex calculations of heat transfer are replaced by a properly defined heat flux boundary condition- the value of which depends on the time of day and meteorological conditions. The model was validated by experimental results from a pilot plant in Manzanares, Spain. Calculations were performed in order to investigate the effects of the chimney’s height and the density of the solar radiation. Both of these dependencies were found to be logarithmic. The requirements for a 250 kW plant in various locations with different meteorological conditions were analyzed.

6

Wpływ wybranych parametrów na ruch cząstki wody w strumieniu spalin

Pająk T., Jurczyk M.

Przemysł Chemiczny

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2018

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T. 97, nr 9

1508--1510

PL

Przedstawiono obszerną analizę ruchu kropli wody w kondycjonerze spalin w spalarni odpadów komunalnych. Badano siły mające wpływ na ruch cząstki bez uwzględnienia wymiany ciepła i masy. Obliczenia wykonano w programach GNU Octave i OpenFoam. Wyniki obliczeń mogą służyć do optymalizacji obliczeń numerycznych procesu kondycjonowania.

EN

Fundamentals and numerical simulation of dynamics of H2O droplets in flue gas stream. The simulated data agreed with results of exp. studies.

7

Grid type impact on the results of the volume of fluid method in the free surface flow calculations around ship hull

Sugalski K., Skrúcaný T.

New Trends in Production Engineering

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2018

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Vol. 1, Iss. 1

151--157

EN

This article presents results of the free surface flow around ship hull on two different types of computational grid. Each type of mentioned grid has its own advantages and disadvantages in particular cases, mostly in one phase simulation. Omitting cases with capitation, there is no free surface involved in one phase simulation. Multiphase simulations are crucial in the ship design process and optimization. Recreating free surface on the triangular mesh causes difficulties, in contrast to the hexahedral meshes, where calculated surface is more aligned to the physical border of the fluids. In this paper, results from the triangular mesh were compared to results from hexahedral mesh. Conclusions about triangular meshes in two phase simulation are presented. The computational fluid dynamic toolbox OpenFOAM is used to perform calculations of the total resistance of work boat in calm water.

8

Numerical Investigation on the Crucible Discharge of Steel and Slag During the Aluminothermic Welding Process

Weiss S., Riehl I., Hantusch J., Gross U.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 1

173--180

EN

The aluminothermic reaction is a type of self-propagating high-temperature synthesis to produce high quality metals and metal oxides en route. The main use of the aluminothermic reaction is in the field of railway welding. The multiphase flow of steel, slag and air in differently shaped crucibles has been numerically investigated in this work with the volume-of-fluid method. The simulations were carried out with the multiphase solver of the open source toolbox OpenFOAM. To validate the numerical results of the three-dimensional simulations, an experiment was carried out to investigate the discharge of a water-oil system from the crucible. A comparison to a numerical 3D simulation showed reasonable accurate results. It can be said that the solver is capable of predicting the point of the oil penetration of the water phase in the experiment.

9

Modelowanie struktur kawitacji przy opływie profilu

Homa D., Wróblewski W.

Modelowanie Inżynierskie

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2017

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T. 32, nr 63

56--64

PL

W artykule przedstawiono wyniki symulacji numerycznych zjawiska kawitacji występującego przy opływie łopatki profilu ClarkY wodą. Przepływ odbywał się w komorze o przekroju prostokątnym. Kąt natarcia łopaty wynosił 8°. Symulacje przeprowadzono przy użyciu kodu OpenFOAM. Dla modelu przepływu dwufazowego prowadzono obliczenia niestacjonarne przy założeniu modelu kawitacji Schnerr & Sauer. Przebadano i porównano dwa modele: model 2D oraz model 3D. Wyniki obliczeń porównano pod względem kształtu i dynamiki zmian chmur kawitacyjnych oraz procentowego udziału pary wodnej w domenie w funkcji czasu. Porównano uśrednione w jednym okresie wartości ciśnienia i udziałów objętościowych pary w punktach monitorujących. Obliczenia dla modelu 3D pozwoliły zaobserwować zmienność struktur kawitacyjnych w kierunku prostopadłym do kierunku przepływu wody.

EN

The results of numerical simulation of water cavitating flow are shown in the paper, in case of flow over the ClarkY foil. The calculations were performed for flow through a rectangular channel. The angle of attack of the blade was 8°. The simulation was conducted in OpenFOAM software. For the two-phase model the transient calculations were carried out with Schnerr & Sauer cavitation model. The two models: 2D and 3D, were investigated and compared. The results of the calculation were compared regarding the shape and dynamics of cavitation structures and percentage of vapor in the domain in time. The time-averaged pressure and vapor volume fraction values in monitor points located over the foil were compared. The 3D calculations provided information about the fluctuation of cavitation structures in the direction perpendicular to the water flow.

10

A Comparison of Simplified Two-dimensional Flow Models Exemplified by Water Flow in a Cavern

Prybytak D., Zima P.

Archives of Hydro-Engineering and Environmental Mechanics

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2017

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Vol. 64, nr 3-4

141--154

EN

The paper shows the results of a comparison of simplified models describing a two-dimensional water flow in the example of a water flow through a straight channel sector with a cavern. The following models were tested: the two-dimensional potential flow model, the Stokes model and the Navier-Stokes model. In order to solve the first two, the boundary element method was employed, whereas to solve the Navier-Stokes equations, the open-source code library OpenFOAM was applied. The results of numerical solutions were compared with the results of measurements carried out on a test stand in a hydraulic laboratory. The measurements were taken with an ADV probe (Acoustic Doppler Velocimeter). Finally, differences between the results obtained from the mathematical models and the results of laboratory measurements were analysed.

11

Investigation of blood flow rheology using second-grade viscoelastic model (Phan-Thien–Tanner) within carotid artery

Ramiar A., Larimi M. M., Ranjbar A. A.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 3

27--41

EN

Purpose: Hemodynamic factors, such as Wall Shear Stress (WSS), play a substantial role in arterial diseases. In the larger arteries, such as the carotid artery, interaction between the vessel wall and blood flow affects the distribution of hemodynamic factors. The fluid is considered to be non-Newtonian, whose flow is governed by the equation of a second-grade viscoelastic fluid and the effects of viscoelastic on blood flow in carotid artery is investigated. Methods: Pulsatile flow studies were carried out in a 3D model of carotid artery. The governing equations were solved using finite volume C++ based on open source code, OpenFOAM. To describe blood flow, conservation of mass and momentum, a constitutive relation of simplified Phan-Thien–Tanner (sPTT), and appropriate relations were used to explain shear thinning behavior. Results: The first recirculation was observed at t = 0.2 s, in deceleration phase. In the acceleration phase from t = 0.3 s to t = 0.5 s, vortex and recirculation sizes in bulb regions in both ECA and ICA gradually increased. As is observed in the line graphs based on extracted data from ICA, at t = 0.2 s, τyy is the maximum amount of wall shear stress and τxy the minimum one. The maximum shear stress occurred in the inner side of the main branch (inner side of ICA and ECA) because the velocity of blood flow in the inner side of the bulb region was maximum due to the created recirculation zone in the opposite side in this area. Conclusions: The rheology of blood flow and shear stress in various important parts (the area that are in higher rates of WSS such as bifurcation region and the regions after bulb areas in both branches, Line1–4 in Fig. 7) were also analyzed. The investigation of velocity stream line, velocity profile and shear stress in various sections of carotid artery showed that the maximum shear stress occurred in acceleration phase and in the bifurcation region between ECA and ICA which is due to velocity gradients and changes in thinning behavior of blood and increasing strain rate in Newtonian stress part.

12

Implementation of Ffowcs Williams and Hawkings aeroacoustic analogy in OpenFOAM

Jarosz K., Czajka I., Gołaś A.

Vibrations in Physical Systems

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2016

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Vol. 27

161--168

EN

This paper presents the development of post-processing aeroacoustics utility for OpenFOAM, based on Ffowcs Williams-Hawkings aeroacoustic analogy. Although the FH-W analogy is well known for almost 50 years, there is a lack of open-source software which is using it, hence decision to perform this implementation. This is the veryfirst version of utility, so only one formulation of FH-W were implemented. Presented application allows to compute far-field acoustic pressure from near field CFD solution. Validation is based on NASA Tandem Cylinder Case. Comparison of the results from simulation show fairly good agreement with experimental data.