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1

Experimental and numerical analyses of airflow around two cylinders angled to the direction of wind

Padewska-Jurczak Agnieszka, Szczepaniak Piotr, Walentyński Ryszard

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 1

art. no. e144578

EN

The analyses aim to determine aerodynamic force coefficients in the case of airflow around two smooth or rough cylinders positioned at different angles to the direction of wind velocity. Such systems, for instance, may be part of a tubular water slide. The results were compared with the values of the interference coefficient of the cylinders arranged in a row included in Eurocode EN 1991 part 4. The aerodynamic forces of the cylinder systems were determined on the basis of experimental tests conducted in a wind tunnel. To verify the above results, CFD (computational fluid dynamics) simulations were prepared. An important observation is that for the angle of yaw β = 0◦, the negative component of the lift force (lateral) fy is shown, while for the other cases, the situation is opposite and the lateral force points outside the gap (upward). The second is that the results of aerodynamic drag for rough cylinders arranged in a row and calculated according to EN 1991 part 4 may be underestimated. The flow around the pair of smooth cylinders is quite different from that of the rough ones, because during the experiment the first falls into the critical flow regime, while the second has supercritical characteristics.

2

Experimental and numerical analysis of blood flow in roughness impact-R test

Kopernik Magdalena, Kruczek Dawid, Kurtyka Przemysław, Pomorska Małgorzata, Major Roman

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 3

120--133

EN

The present paper covers simulation of blood flow in a roughness impact-R test model to anticipate the hemodynamic conditions of adhesion of blood elements to the modified surface. It was performed using numerical modelling of this process. The aim of these simulations was to create a surface morphology that stimulates the adhesion of blood elements to the surface of base plate of impact-R test. Methods: The morphology of base plate of impact-R test was developed using a vacuum powder sintering of commercial purity titanium powder (CP-Ti) on Ti6Al7Nb substrate. The finite volume method (FVM) and disperse particle method (DPM) were applied to develop the target model of a roughness impact-R test. The morphology of modified surfaces was documented with digital microscope and SEM (scanning electron microscopy). Results: The impact-R test developed using the two-phase blood model performed on regularly structured base plate resulted in shear stress values higher than the analogous for the model lacking such modification. The most significant reduction in maximum values of shear stress occurred in case of the DPM model and especially in the model with regular structures. Conclusions: The proposed models are very effective in modeling of the analysis of blood flow in roughness impact-R test.

3

Discrete phase model of blood flow in a roughness microchannel simulating the formation of pseudointima

Kopernik Magdalena, Dyrda Karina, Kurtyka Przemysław, Major Roman

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 1

132--144

EN

The goal of the present study was the development of discrete phase model to simulate the phenomenon of backfilling a morphologically complex surface by red blood cells (RBCs) in a flow microchannel and to anticipate the conditions of forming a pseudointima. The objective of the experimental studies that inspired the development of the simulation was to create a surface that stimulates the formation of the pseudointima layer. Methods: The finite volume method (FVM) and discrete particle method (DPM) were applied to develop the target model. In addition, a mixture model and a roughness model of bottom layer were tested in the present study to show their influence on simulation the phenomenon of backfilling a morphologically complex surface by RBCs in a flow microchannel. Results: Numerical models were developed including: a) FVM models to compare the effect of applying boundary conditions with/without roughness and cubes, as well as the analysis of their influence on blood velocity and shear stress; b) mixture models to compare the effect of applying different boundary conditions and cubes on computed results; c) DPM models to compare the effect of applying and not applying roughness as a boundary condition; d) DPM models with a morphologically complex surface and RBCs collisions to present RBCs concentration, velocity and time distributions during flow in a channel. Conclusions: The analysis carried out for the developed numerical models indicates that DPM model with cubes computes the best results. It also shows the backfilling of a morphologically complex surface of the bottom microchannel with RBCs.

4

Towards optimal design of energy efficient buildings

Gajewski R. R., Kułakowski T.

Archives of Civil Engineering

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2018

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Vol. 64, nr 4/II

135--153

EN

Buildings consume half of all energy use and are also responsible for a similar proportion of carbon dioxide emission. The heat transfer across the building envelope - the shell of a house that separates the inside and outside - should generally be minimized. In the paper validation and verification based on Building Energy Simulation Test (BESTEST) of Energy3D computer code is presented. Next, computations performed by means of Energy 3D and Energy Plus for BESTEST building are compared. In the last part of the paper results for computations for real building are presented. Program Energy 3D proved to be an excellent tool for qualitative and quantitative analysis of buildings with respect to energy consumption.

PL

W związku ze znaczącym udziałem budynków w globalnym zapotrzebowaniu na energię ich projektowanie staje się coraz bardziej ukierunkowane na efektywne wykorzystanie nieodnawialnych zasobów takich jak np. paliwa kopalne. Celem niniejszej publikacji jest prezentacja możliwości jakie daje wykorzystanie oprogramowania do symulacji energetycznych budynków przy ich projektowaniu. We współpracy z firmą Wienerberger, która udostępniła dane dotyczące ich budynku modelowego oraz wyniki symulacji przeprowadzonych przez Narodową Agencję Poszanowania Energii S.A. w ramach optymalizacji jego projektu, autorzy porównali możliwości przykładowych, dostępnych komercyjnie narzędzi symulacyjnych – Energy3D oraz EnergyPlus (Design Builder) oraz porównali z wynikami benchmarkowymi na przykładzie budynku BESTEST. Poza omówieniem założeń obliczeniowych, a także dostępnych funkcjonalności programów, niniejszy artykuł zawiera streszczenie zagadnień wymagających rozwiązania przy symulacjach dynamicznej wymiany ciepła w budynkach oraz wybrane metody obliczeniowe stosowane w komercyjnych programach komputerowych.

5

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.

6

Porównanie sił aerodynamicznych działających na połowę torusa i dwa walce o tej samej długości

Padewska A., Szczepaniak P., Wawrzynek A.

Modelowanie Inżynierskie

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2016

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T. 29, nr 60

52--57

PL

W Eurokodzie PN-EN 1991-1-4 [11] brakuje wytycznych projektowych umożliwiających oszacowanie sił aerodynamicznych działających na obiekty o nietypowym kształcie. W referacie porównano zatem charakter przepływu powietrza o dużych, coraz częściej występujących na świecie prędkościach w pobliżu obiektów w kształcie połowy torusa (np. fragmentu zjeżdżalni wodnej) i dwóch walców o sumarycznej długości równej długości osi połowy torusa, ustawionych poziomo oraz odchylonych od poziomej płaszczyzny pod kątem ß = 45°. Porównano również siły aerodynamiczne działające na połowę torusa - opór aerodynamiczny i poziomą siłę prostopadłą do niego, z siłami działającymi na walce. Wyniki otrzymano na podstawie analiz numerycznych: MES i MOS, wykorzystując moduły: CFD (Computational Fluid Dynamics) i FSI (Fluid-Structure Interaction).

EN

Eurocode EN 1991-1-4 [11] does not include issues concerning wind loads acting on constructions in a non-typical shape. Therefore, in the paper the character of high-speed air flow, which increasingly occurs in the world around objects in the shape of a half - torus (eg. a fragment of a water slide) and two cylinders positioned horizontally and inclined to the horizontal plane at an angle ß = 45° were compared. Also aerodynamic forces acting on a half of the torus - an aerodynamic resistance and a horizontal force perpendicular to the direction of a wind velocity, were compared with forces acting on cylinders. Results are based on numerical analysis: FEM and FVM using the following modules: CFD (Computational Fluid Dynamics) and FSI (Fluid-Structure Interaction).

7

Analysis of fluid-structure interaction of a torus subjected to wind loads

Padewska A., Szczepaniak P., Wawrzynek A.

Computer Assisted Methods in Engineering and Science

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2014

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Vol. 21, no. 2

151--167

EN

In the paper the aerodynamic forces acting on a part of a water slide or other object with curved, tubular shape, depending on the section of a torus and value of the wind velocity, were obtained. This was done by means of finite element method (FEM) and finite volume method (FVM) computer simulations, using modules: computational fluid dynamics (CFD) and fluid-structure interaction (FSI) and taking into account the Eurocode EN 1991-1-4.

8

Thermomechanical coupling between the flow of steam and deformation of the valve during start-up of the 200 MW turbine

Bielecki M., Karcz M., Radulski W., Badur J.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2001

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Vol. 5, No 2

125-140

EN

The lifetime estimation of power station structures and components, subjected to fatigue loading, is essential for determining the moment of repair or replacement. Therefore the degradation behaviour and damage development within material should be very well understood. This research focuses on a fluid-solid interaction that has been developed in Finite Volume Method software for description of heat and flow loading on a cut-off valve and Finite Element Method software for conduct researches on fatigue and creep damage of the valve material.