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219 results on '"Jakirlić, Suad"'

1. Flow in a Concentric Annulus with Inner- or Outer-Cylinder Rotation: A Conventional and Sensitized RANS Modelling Study

Author

Wang, Xiaoyu, Hussong, Jeanette, Jakirlic, Suad, Hirschel, Ernst Heinrich, Founding Editor, Schröder, Wolfgang, Series Editor, Boersma, Bendiks Jan, Editorial Board Member, Fujii, Kozo, Editorial Board Member, Haase, Werner, Editorial Board Member, Leschziner, Michael A., Editorial Board Member, Periaux, Jacques, Editorial Board Member, Pirozzoli, Sergio, Editorial Board Member, Rizzi, Arthur, Editorial Board Member, Roux, Bernard, Editorial Board Member, Shokin, Yurii I., Editorial Board Member, Lagemann, Esther, Managing Editor, Dillmann, Andreas, editor, Heller, Gerd, editor, Krämer, Ewald, editor, Wagner, Claus, editor, and Weiss, Julien, editor

Published
2024
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5. Impact of Supercooled Drops onto Cold Surfaces

Author

Gloerfeld, Mark, Schremb, Markus, Criscione, Antonio, Jakirlic, Suad, Tropea, Cameron, Thess, André, Series Editor, Moreau, René, Founding Editor, Schulte, Kathrin, editor, Tropea, Cameron, editor, and Weigand, Bernhard, editor

Published
2022
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6. Insights into the Periodic Gust Response of Airfoils

Author

Wei, Nathaniel J., Kissing, Johannes, Wester, Tom T. B., Wegt, Sebastian, Schiffmann, Klaus, Jakirlic, Suad, Hölling, Michael, Peinke, Joachim, and Tropea, Cameron

Subjects
Physics - Fluid Dynamics
Abstract

The unsteady lift response of an airfoil in a sinusoidal gust can be modeled by two transfer functions: the first-order Sears function and the second-order Atassi function, albeit leading to different results under certain conditions. Previous studies have shown that the Sears function holds in experiments, but recently Cordes et al. (2017) reported experimental data that corresponded to the Atassi function rather than the Sears function. In order to clarify the observed discrepancy, the specific differences between these models are isolated analytically in this study and are related to physical gust parameters. Gusts with these parameters are then produced in wind-tunnel experiments using an active-grid gust generator. Measurements of the unsteady gust loads on an airfoil in the wind tunnel at Reynolds numbers ($Re_c$) of $2.0\times 10^5$ and $2.6\times 10^5$ and reduced frequencies between 0.09 and 0.42 confirm that the decisive difference between the Sears and Atassi functions lies in the character of the gust and not in the characteristics of the airfoil. The differences in the gust-response data between Sears and Atassi gust conditions are shown to be significant only at low reduced frequencies. These findings are supported by numerical simulations of the experimental setup. Finally, the influence of boundary-layer turbulence on experimental convergence with model predictions is investigated. These results serve to clarify the conditions under which the Sears and Atassi functions can be applied, and they establish the validity of both in an experimental context., Comment: This manuscript is currently under review

Published
2018
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7. A Scale-Resolving Elliptic-Relaxation-Based Eddy-Viscosity Model: Development and Validation

Author

Krumbein, Benjamin, Maduta, Robert, Jakirlić, Suad, Tropea, Cameron, Hirschel, Ernst Heinrich, Founding Editor, Schröder, Wolfgang, Series Editor, Boersma, Bendiks Jan, Series Editor, Fujii, Kozo, Series Editor, Haase, Werner, Series Editor, Leschziner, Michael A., Series Editor, Periaux, Jacques, Series Editor, Pirozzoli, Sergio, Series Editor, Rizzi, Arthur, Series Editor, Roux, Bernard, Series Editor, Shokin, Yurii I., Series Editor, Dillmann, Andreas, editor, Heller, Gerd, editor, Krämer, Ewald, editor, Wagner, Claus, editor, Tropea, Cameron, editor, and Jakirlić, Suad, editor

Published
2020
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8. Preliminary Investigations on Aerodynamic Vehicle Optimization Using the Adjoint Method with Adjoint Turbulence

Author

Behnsch, Martin, Schütz, T., Jakirlić, Suad, Tropea, Cameron, Hirschel, Ernst Heinrich, Founding Editor, Schröder, Wolfgang, Series Editor, Boersma, Bendiks Jan, Series Editor, Fujii, Kozo, Series Editor, Haase, Werner, Series Editor, Leschziner, Michael A., Series Editor, Periaux, Jacques, Series Editor, Pirozzoli, Sergio, Series Editor, Rizzi, Arthur, Series Editor, Roux, Bernard, Series Editor, Shokin, Yurii I., Series Editor, Dillmann, Andreas, editor, Heller, Gerd, editor, Krämer, Ewald, editor, Wagner, Claus, editor, Tropea, Cameron, editor, and Jakirlić, Suad, editor

Published
2020
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9. Scrutinizing Conventional and Eddy-Resolving Unsteady RANS Approaches in Computing the Flow and Aeroacoustics Past a Tandem Cylinder

Author

Köhler, Felix, Maduta, Robert, Krumbein, Benjamin, Jakirlić, Suad, Hirschel, Ernst Heinrich, Founding Editor, Schröder, Wolfgang, Series Editor, Boersma, Bendiks Jan, Series Editor, Fujii, Kozo, Series Editor, Haase, Werner, Series Editor, Leschziner, Michael A., Series Editor, Periaux, Jacques, Series Editor, Pirozzoli, Sergio, Series Editor, Rizzi, Arthur, Series Editor, Roux, Bernard, Series Editor, Shokin, Yurii I., Series Editor, Dillmann, Andreas, editor, Heller, Gerd, editor, Krämer, Ewald, editor, Wagner, Claus, editor, Tropea, Cameron, editor, and Jakirlić, Suad, editor

Published
2020
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19. Computational Study of Mean Flow and Turbulence Structure in Inflow System of a Swirl Combustor

Author

Šarić, Sanjin, Jakirlić, Suad, Čavar, Dalibor, Kniesner, Björn, Altenhöfer, Paul, Tropea, Cameron, Hirschel, E. H., editor, Schröder, W., editor, Fujii, K., editor, Haase, W., editor, van Leer, B., editor, Leschziner, M. A., editor, Pandolfi, M., editor, Periaux, J., editor, Rizzi, A., editor, Roux, B., editor, Shokin, Yu., editor, Tropea, Cameron, editor, Jakirlic, Suad, editor, Heinemann, Hans-Joachim, editor, Henke, Rolf, editor, and Hönlinger, Heinz, editor

Published
2008
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23. LES, Zonal and Seamless Hybrid LES/RANS: Rationale and Application to Free and Wall-Bounded Flows Involving Separation and Swirl

Author

Jakirlić, Suad, Manceau, Rémi, Šarić, Sanjin, Fadai-Ghotbi, Atabak, Kniesner, Björn, Carpy, Sabrina, Kadavelil, Gisa, Friess, Christophe, Tropea, Cameron, Borée, Jacques, Hirschel, Ernst Heinrich, editor, Schröder, Wolfgang, editor, Fujii, Kozo, editor, Haase, Werner, editor, van Leer, Bram, editor, Leschziner, Michael A., editor, Pandolfi, Maurizio, editor, Periaux, Jacques, editor, Rizzi, Arthur, editor, Roux, Bernard, editor, Shokin, Yurii I., editor, Brun, Christophe, editor, Juvé, Daniel, editor, Manhart, Michael, editor, and Munz, Claus-Dieter, editor

Published
2009
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32. A tandem approach for collocated measurements of microphysical and radiative cirrus properties

Author

Klingebiel, Marcus, Ehrlich, André, Finger, Fanny, Röschenthaler, Timo, Jakirlić, Suad, Voigt, Matthias, Müller, Stefan, Maser, Rolf, Wendisch, Manfred, Hoor, Peter, Spichtinger, Peter, and Borrmann, Stephan

Abstract

Microphysical and radiation measurements were collected with the novel AIRcraft TOwed Sensor Shuttle (AIRTOSS) – Learjet tandem platform. The platform is a combination of an instrumented Learjet 35A research aircraft and an aerodynamic bird, which is detached from and retracted back to the aircraft during flight via a steel wire with a length of 4000 m. Both platforms are equipped with radiative, cloud microphysical, trace gas, and meteorological instruments. The purpose of the development of this tandem set-up is to study the inhomogeneity of cirrus as well as other stratiform clouds. Sophisticated numerical flow simulations were conducted in order to optimally integrate an axially asymmetric Cloud Combination Probe (CCP) inside AIRTOSS. The tandem platform was applied during measurements at altitudes up to 36 000 ft (10 970 m) in the framework of the AIRTOSS – Inhomogeneous Cirrus Experiment (AIRTOSS-ICE). Ten flights were performed above the North Sea and Baltic Sea to probe frontal and in situ formed cirrus, as well as anvil outflow cirrus. For one flight, cirrus microphysical and radiative properties displayed significant inhomogeneities resolved by both measurement platforms. The CCP data show that the maximum of the observed particle number size distributions shifts with decreasing altitude from 30 to 300 µm, which is typical for frontal, midlatitude cirrus. Theoretical considerations imply that cloud particle aggregation inside the studied cirrus is very unlikely. Consequently, diffusional growth was identified to be the dominant microphysical growth process. Measurements of solar downward and upward irradiances at 670 nm wavelength were conducted above, below, and in the cirrus on both the Learjet and AIRTOSS. The observed variability of the downward irradiance below the cirrus reflects the horizontal heterogeneity of the observed thin cirrus. Vertically resolved solar heating rates were derived by either using single-platform measurements at different altitudes or by making use of the collocated irradiance measurements at different altitudes of the tandem platform. Due to unavoidable biases of the measurements between the individual flight legs, the single-platform approach failed to provide a realistic solar heating rate profile, while the uncertainties of the tandem approach are reduced. Here, the solar heating rates range up to 6 K day−1 at top of the cirrus layer.

Published
2018

35. Progress in the second-moment closure for bubbly flow based on direct numerical simulation data.

Author

Ma, Tian, Lucas, Dirk, Jakirlić, Suad, and Fröhlich, Jochen

Subjects
COMPUTER simulation, CHANNEL flow, TURBULENCE, EDDY viscosity
Abstract

Data from direct numerical simulations (DNS) of disperse bubbly flow in an upward vertical channel are used to develop a new second-moment closure for bubble-induced turbulence (BIT) in the Euler–Euler framework. The closure is an extension of a BIT model originally proposed by Ma et al. (Phys. Rev. Fluids, vol. 2, 2017, 034301) for two-equation eddy-viscosity models and focuses on the core region of the channel, where the interfacial term and dissipation term are in balance. Particular attention in this study is given to the treatment of the pressure–strain term for bubbly flows and the form of the interfacial term to account for BIT. For the latter, the concept of an effective BIT source is proposed, which leads to a significant simplification of the modelling work for both the pressure–strain correlation and the interfacial term itself. The anisotropy of bubbly flow is analysed with the aid of the anisotropy-invariant map obtained from the DNS data, and a parameter governing this issue is established. The complete second-moment closure is tested against reference data for different bubbly channel flows and a case of a bubble column. The agreement achieved with the DNS data is very good and the performance of the new model is better than obtained with the standard procedure. Furthermore, the model is shown to be robust and to fulfil the requirements of realizability. [ABSTRACT FROM AUTHOR]

Published
2020
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36. A tandem approach for collocated measurements of microphysical and radiative cirrus properties

Author

Klingebiel, Marcus, primary, Ehrlich, André, additional, Finger, Fanny, additional, Röschenthaler, Timo, additional, Jakirlić, Suad, additional, Voigt, Matthias, additional, Müller, Stefan, additional, Maser, Rolf, additional, Wendisch, Manfred, additional, Hoor, Peter, additional, Spichtinger, Peter, additional, and Borrmann, Stephan, additional

Published
2017
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38. A tandem approach for collocated in-situ measurements of microphysical and radiative cirrus properties

Author

Klingebiel, Marcus, primary, Ehrlich, André, additional, Finger, Fanny, additional, Röschenthaler, Timo, additional, Jakirlić, Suad, additional, Voigt, Matthias, additional, Müller, Stefan, additional, Maser, Rolf, additional, Wendisch, Manfred, additional, Hoor, Peter, additional, Spichtinger, Peter, additional, and Borrmann, Stephan, additional

Published
2017
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41. A tandem approach for collocated in-situ measurements of microphysical and radiative cirrus properties.

Author

Klingebiel, Marcus, Ehrlich, André, Finger, Fanny, Röschenthaler, Timo, Jakirlić, Suad, Voigt, Matthias, Müller, Stefan, Maser, Rolf, Wendisch, Manfred, Hoor, Peter, Spichtinger, Peter, and Borrmann, Stephan

Subjects
RADIATION measurements, DETECTORS
Abstract

Microphysical and radiation measurements were collected with the unique AIRcraft TOwed Sensor Shuttle (AIRTOSS) - Learjet tandem platform. It is a combination of a Learjet 35A research aircraft and an instrumented aerodynamic body, which can be detached from and retracted back to the aircraft during flight. Both platforms are equipped with radiative, cloud microphysical, trace gas (CO, N2O, O3 and H2O) and meteorological instruments to study the inhomogeneity of cirrus as well as other layer clouds. Sophisticated numerical flow simulations were conducted in advance in order to optimally integrate a Cloud Combination Probe (CCP) inside the AIRTOSS. The tandem platform was used for the first time at altitudes up to 36?000?ft (10?970?m) during the AIRTOSS - Inhomogeneous Cirrus Experiment (AIRTOSS-ICE). AIRTOSS is connected to the aircraft by a steel wire with a length of 4000?m. Ten flights were performed above the North Sea and Baltic Sea to probe frontal cirrus, in-situ formed cirrus, and anvil outflow cirrus. The cirrus microphysical and radiative properties displayed significant inhomogeneities resolved by both measurement platforms. Data collected with the CCP show that the maximum of the observed particle number size distributions shifts with increasing altitude from 300?μm to 30 ?μm, which is typical for frontal, midlatitude cirrus. Theoretical considerations imply that cloud particle aggregation inside the studied cirrus is very unlikely. Consequently, diffusional growth was identified to be the dominant microphysical process. Measurements of solar downward irradiance at 670?nm wavelength on the Learjet and the sensor shuttle indicate a significant horizontal heterogeneity of the observed thin cirrus. Making use of the collocated irradiance measurements of the tandem platform, vertically resolved solar heating rates were derived. They varied by up to 6?K?day-1 in and above the cirrus layer. [ABSTRACT FROM AUTHOR]

Published
2017
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46. Preface

Author

Jakirlić, Suad, primary, Launder, Brian E., additional, Schmidt, Frank W., additional, and Tavoularis, Stavros, additional

Published
2012
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50. Computational Study of Mean Flow and Turbulence Structure in Inflow System of a Swirl Combustor.

Author

Hirschel, E. H., Schröder, W., Fujii, K., Haase, W., van Leer, B., Leschziner, M. A., Pandolfi, M., Periaux, J., Rizzi, A., Roux, B., Shokin, Yu., Jakirlic, Suad, Heinemann, Hans-Joachim, Henke, Rolf, Hönlinger, Heinz, Šarić, Sanjin, Jakirlić, Suad, Čavar, Dalibor, Kniesner, Björn, and Altenhöfer, Paul

Abstract

Flow structure in the annular section of the inlet system of a tuboannular swirl combustor with respect to the swirl intensity influence was investigated computationally complementary to the recent experimental study by Palm et al. [1]. In addition to the non-swirling case, two different swirling configurations corresponding to the swirl numbers S = 0.6 and 1.0 were considered. The simulations were performed by using Large Eddy Simulation (LES) method and a two-layer model scheme hybridizing a near-wall k —ε RANS (Reynolds-averaged Navier Stokes) model covering the wall layer and LES method in the outer layer employing Smagorinsky model. Special attention was devoted to the position of the interface. An in-depth analysis of the mean velocity and turbulence fields reveals an increasingly asymmetric axial velocity profile in the annular pipe and an appropriately shaped profile of the Reynolds stress components corresponding to the enhanced turbulence production in the outer part of the concentric annulus. The present study also aimes at generation of reliable swirling inflow data for future LES of the flow in the combustor flue. [ABSTRACT FROM AUTHOR]

Published
2008
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