TY - GEN A1 - Zanoun, El-Sayed A1 - Bauer, Christian A1 - Wagner, Claus A1 - Durst, Franz A1 - Egbers, Christoph A1 - Bellani, Gabriele A1 - Talamelli, Alessandro T1 - Cross-validation of numerical and experimental data in turbulent pipe flow with new scaling correlations T2 - Journal of turbulence N2 - The dependence of turbulence statistics and wall friction on Reynolds number in fully developed turbulent pipe flow remains a fundamental subject in fluid mechanics. This paper cross-validates experimental and numerical results, focusing on the scaling of turbulence statistics at the pipe centerline and across the inner-outer flow region. Pipe flow experiments were reviewed for friction Reynolds numbers 810≤Re𝜏≤55×103, where Re𝜏=𝑢𝜏⁢𝑅/𝜈, 𝑢𝜏 is the wall friction velocity, 𝑅 the pipe radius, and 𝜈 the kinematic viscosity. Complementary DNS data for 180≤Re𝜏≤2880 provide detailed insight into near-wall turbulence. A novel friction correlation, Re𝜏=0.048Re0.923 c is introduced, predicting pipe-wall friction across a wide range of Re𝑐 with accuracy better than ±2.06%, where Re𝑐 is the Reynolds number based on the centerline streamwise mean velocity component 𝑈zc. This correlation enables reliable friction estimates from centerline single-point measurements or DNS data without requiring near-wall or streamwise pressure-gradient information and is validated by consistent agreement with both experiments and DNS. The monotonic decrease in centerline turbulence intensity ⟨𝑢′𝑧2⟩1/2/𝑈zc with increasing Re𝑐 is explained using the streamwise mean momentum equation. Finally, azimuthal spatial filtering of DNS data highlights the limitations of hot-wire resolution near the wall. For Re𝜏≥2880, higher-order experimental statistics agree well with DNS for 𝑦+≥30 and into the logarithmic region, with both datasets equally well described by logarithmic or power-law correlations, while near-wall discrepancies remain due to resolution limits. KW - Pipe flow KW - Turbulence statistics KW - DNS KW - Experiments Y1 - 2025 U6 - https://doi.org/10.1080/14685248.2025.2560314 SP - 1 EP - 22 PB - Taylor & Francis CY - London ER - TY - GEN A1 - Hamede, Mohammed Hussein A1 - Sliavin, Yaraslau A1 - Motuz, Vasyl A1 - Egbers, Christoph T1 - The effect of flow initial conditions and geometry on the saturation of the thermo-electrohydrodynamic instability within microgravity conditions T2 - Physics of fluids N2 - The present study investigates the thermo-electrohydrodynamic-induced convection in a dielectric fluid confined between two concentric differentially heated cylinders under microgravity conditions through experimental means. The experiments were conducted during parabolic flight campaigns. In the present study, our primary focus was on the saturation of perturbations induced by thermo-electrohydrodynamic instability. The effect of initial flow conditions on perturbation growth rates is examined when entering the microgravity phase. Furthermore, a series of experimental setups with varied lengths and aspect ratios were considered to investigate the impact of geometry on flow behavior. The present study quantitatively investigated the flow using particle image velocimetry in the meridional and radial–azimuthal planes. Furthermore, direct measurements were taken of the global response of the flow, in this case heat transfer, using a heat flux sensor attached to the outer cylinder wall. KW - Heat transfer KW - Electrostatics KW - Microgravity KW - Dielectric materials KW - Fluid instabilities KW - Fluid dynamics KW - Flow instabilities KW - Flow visualization Y1 - 2025 U6 - https://doi.org/10.1063/5.0287547 VL - 37 IS - 9 SP - 1 EP - 10 PB - AIP Publishing CY - College Park, Maryland ER - TY - GEN A1 - Barzantny, Marcel A1 - Hamede, Mohammed Hussein A1 - Majchrzyk, Michał A1 - Merbold, Sebastian A1 - Egbers, Christoph A1 - Kostowski, Wojciech T1 - Experimental investigation of the flow characteristics driving the Ranque–Hilsch phenomenon T2 - International journal of heat and mass transfer N2 - The Ranque–Hilsch vortex tube (RHVT) is a device that separates a pressurized inlet stream into two decompressed streams of different temperature, flowing to the so-called hot and cold outlets. In this study, the flow structures within the vortex tube were examined qualitatively. The examination considered both compressible and incompressible fluids, using pressurized air and water as working fluids. A parametric study was conducted, in which the fluid inlet pressure and the vortex tube length were varied. Three tubes, with the same diameter but differing lengths (100, 180, and 240 mm) were utilized. The flow inside the tube was investigated using a flow visualization technique, which was employed in a variety of configurations and setups contingent on the specific fluid conditions under examination. The visualization process required the use of aerosol injection in the case of air, and kalliroscope particles in the case of water investigation. The research enabled the visualization of the flow structure within the vortex tube, thereby significantly advancing the comprehension of the underlying physical processes. The findings of the experimental research demonstrated the existence of phenomena of considerable scientific value. The internal vortex and its spatial and temporal structure observed in the RHVT were consistent with literature data. This was achieved despite the so-far established consensus that this type of research is challenging and not entirely reliable. In the course of water-based investigation, the cavitation phenomenon was observed in the vicinity of the internal vortex. This discovery is likely to be the first of its kind and may contribute significantly to the advancement of research on the Ranque–Hilsch phenomenon. KW - Ranque–Hilsch phenomenon KW - Vortex tube KW - Flow visualization KW - Cavitation Y1 - 2025 U6 - https://doi.org/10.1016/j.ijheatmasstransfer.2025.127543 SN - 0017-9310 VL - 253 SP - 1 EP - 14 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Travnikov, Vadim A1 - Szabo, Peter A1 - Gaillard, Yann A1 - Egbers, Christoph T1 - Centrifugally-driven spherical gap convection with polar angle-dependent boundary condition : can the Nusselt number fall below unity? T2 - Physics of fluids Y1 - 2025 U6 - https://doi.org/10.1063/5.0281082 SN - 1089-7666 VL - 37 SP - 1 EP - 15 PB - American Institute of Physics CY - New York ER - TY - GEN A1 - Szabo, Peter A1 - Egbers, Christoph T1 - Dielectrophoretic-driven thermoelectrohydrodynamic convection in a dielectric fluid layer induced by an inhomogeneous external electric field T2 - Physical review E Y1 - 2025 U6 - https://doi.org/10.1103/PhysRevE.111.045105 SN - 2470-0053 VL - 111 SP - 1 EP - 9 PB - American Physical Society CY - College Park, MD ER - TY - GEN A1 - Hasanuzzaman, Gazi A1 - Egbers, Christoph T1 - Application of machine learning for sustainable aviation : the role of friction drag and flow control in turbulent boundary layer flows T2 - The 2nd International Conference on Advancing Sustainable Futures (ICASF 2024) Y1 - 2024 U6 - https://doi.org/10.13140/RG.2.2.31060.92807 SP - 1 EP - 8 ER - TY - GEN A1 - Shahirpour, Amir A1 - Egbers, Christoph A1 - Sesterhenn, Jörn T1 - Detection of energetic low dimensional subspaces in spatio-temporal space in turbulent pipe flow T2 - Springer Nature Y1 - 2025 U6 - https://doi.org/10.1007/s10494-024-00600-z IS - Volume 114 SP - 1017 EP - 1041 ER - TY - GEN A1 - Hasanuzzaman, Gazi A1 - Buchwald, Tom A1 - Schunk, Christoph A1 - Schröder, Andreas A1 - Egbers, Christoph A1 - Hampel, Uwe T1 - DATIV—remote enhancement of smart aerosol measurement system using raspberry Pi-based distributed sensors T2 - Sensors N2 - Enclosed public spaces are hotspots for airborne disease transmission. To measure and maintain indoor air quality in terms of airborne transmission, an open source, low cost and distributed array of particulate matter sensors was developed and named Dynamic Aerosol Transport for Indoor Ventilation, or DATIV, system. This system can use multiple particulate matter sensors (PMSs) simultaneously and can be remotely controlled using a Raspberry Pi-based operating system. The data acquisition system can be easily operated using the GUI within any common browser installed on a remote device such as a PC or smartphone with a corresponding IP address. The software architecture and validation measurements are presented together with possible future developments. KW - Aerosol transport, indoor ventilation, sensors, measurement, aerodynamics Y1 - 2024 UR - https://www.mdpi.com/1424-8220/24/13/4314 U6 - https://doi.org/10.3390/s24134314 VL - 24 SP - 1 EP - 12 ER - TY - GEN A1 - Simon, Kühne A1 - Yaraslau, Sliavin A1 - Szabo, Peter A1 - Carter, R. A1 - Krebs, Andreas A1 - Egbers, Christoph T1 - Simultaneous particle image velocimetry and background oriented schlieren measurements of convective flows T2 - Experimentelle Strömungsmechanik, Hrsg.: B. Ruck et al. Y1 - 2024 UR - https://www.researchgate.net/publication/384774435_Simultaneous_Particle_Image_Velocimetry_and_Background_Oriented_Schlieren_measurements_of_convective_flows SN - 978-3-9816764-4-0 PB - German Association for Laser Anemometry 26.8 GALA e.V. CY - Karlsruhe ER - TY - GEN A1 - Kühne, Simon A1 - Sliavin, Yaraslau A1 - Szabo, Peter A1 - Carter, Richard A1 - Krebs, Andreas A1 - Egbers, Christoph T1 - Phase-demodulation of interferograms of thermo-electrohydrodynamic convection in a differentially heated cylindrical annulus T2 - Experimentelle Strömungsmechanik : 31. Fachtagung, 3.-5. September 2024, Berlin / Herausgeber: C. Rauh, B. Ruck, A. Leder Y1 - 2024 UR - https://www.researchgate.net/publication/384772995_Phase-demodulation_of_interferograms_of_thermo-electrohydrodynamic_convection_in_a_differentially_heated_cylindrical_annulus SN - 978-3-9816764-4-0 SP - 7.1. EP - 7.8 PB - German Association for Laser Anemometry 26.8 GALA e.V. CY - Karlsruhe ER - TY - GEN A1 - Hamede, Mohammed Hussein A1 - Roller, Jonas A1 - Meyer, Antoine A1 - Heauveline, Vincent A1 - Egbers, Christoph T1 - Dielectrophoretic force-enhanced thermal convection within a horizontal cylindrical annulus T2 - Physics of Fluids Y1 - 2024 U6 - https://doi.org/10.1063/5.0234772 VL - 36 IS - 12 SP - 1 EP - 14 PB - AIP Publishing ER - TY - GEN A1 - Gaillard, Yann A1 - Szabo, Peter A1 - Travnikov, Vadim A1 - Egbers, Christoph T1 - Modelling Thermo-Electrohydrodynamic Convection in Rotating Spherical Shell Using OpenFOAM ® T2 - OpenFOAM® Journal Y1 - 2025 U6 - https://doi.org/10.51560/ofj.v5.136 VL - 5 (2025) SP - 1 EP - 16 ER - TY - GEN A1 - Hasanuzzaman, Gazi A1 - Egbers, Christoph T1 - Flow control of a turbulent boundary layer using uniform blowing T2 - Progress in Turbulence X : Proceedings of the iTi Conference on Turbulence 2023 Y1 - 2024 SN - 978-3-031-55924-2 SN - 978-3-031-55923-5 U6 - https://doi.org/10.1007/978-3-031-55924-2_36 ER - TY - GEN A1 - Meyer, Antoine A1 - Meier, Martin A1 - Motuz, Vasyl A1 - Egbers, Christoph T1 - Thermo-electric convection in a cylindrical annulus during a sounding rocket flight T2 - Journal of Fluid Mechanics Y1 - 2023 U6 - https://doi.org/10.1017/jfm.2023.677 SN - 0022-1120 VL - 972 IS - A26 ER - TY - GEN A1 - Buchwald, Tom A1 - Hasanuzzaman, Gazi A1 - Merbold, Sebastian A1 - Schanz, Daniel A1 - Egbers, Christoph A1 - Schröder, Andreas T1 - Large-scale flow field and aerosol particle transport investigations in a classroom using 2D-Shake-The-Box Lagrangian Particle Tracking T2 - Heliyon Y1 - 2023 U6 - https://doi.org/10.1016/j.heliyon.2023.e22826 SN - 2405-8440 VL - 9 IS - 12 ER - TY - GEN A1 - Zanoun, El-Sayed A1 - Dewidar, Yasser A1 - Egbers, Christoph T1 - Reynolds number dependence of azimuthal and streamwise pipe flow structures T2 - Journal of Fluid Mechanics Y1 - 2023 U6 - https://doi.org/10.1017/jfm.2023.700 SN - 0022-1120 VL - Vol. 973 SP - 1 EP - 36 ER - TY - GEN A1 - Gaillard, Yann A1 - Szabo, Peter A1 - Travnikov, Vadim A1 - Egbers, Christoph T1 - Thermo-electrohydrodynamic convection in a rotating shell with central force field T2 - International Journal of Heat and Mass Transfer Y1 - 2024 U6 - https://doi.org/10.1016/j.ijheatmasstransfer.2023.124760 SN - 0017-9310 VL - Vol. 2018 SP - 1 EP - 12 ER - TY - GEN A1 - Barry, Elhadj A1 - Yoshikawa, Harunori A1 - Kang, Changwoo A1 - Meyer, Antoine A1 - Meier, Martin A1 - Crumeyrolle, Olivier A1 - Egbers, Christoph A1 - Mutabazi, Innocent T1 - Thermoelectric convection in a planar capacitor: theoretical studies and experiments in parabolic flights T2 - Comptes Rendus Mécanique Y1 - 2023 UR - https://comptes-rendus.academie-sciences.fr/mecanique/articles/10.5802/crmeca.143/ SN - 1873-7234 SP - 1 EP - 15 ER - TY - GEN A1 - Hamede, Mohammed Hussein A1 - Merbold, Sebastian A1 - Egbers, Christoph T1 - Transition to the ultimate turbulent regime in a very wide gap Taylor-Couette flow (η = 0.1) with a stationary outer cylinder T2 - EPL (Europhysics Letters) Y1 - 2023 U6 - https://doi.org/10.1209/0295-5075/acdea1 SN - 1286-4854 VL - 143 IS - 2 ER - TY - GEN A1 - Richter, Stefan A1 - Zanoun, El-Sayed A1 - Peixinho, Jorge A1 - Egbers, Christoph T1 - Pipe Flow Development and Transition in CoSmaPipe Facility T2 - Proceedings in applied mathematics and mechanics : PAMM Y1 - 2023 U6 - https://doi.org/10.1002/pamm.202300001 SN - 1617-7061 N1 - 92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) May 2023 VL - 23 IS - 1 ER -