Moritz Sieber
YOU?
Author Swipe
View article: Data-driven spatiotemporal analysis of cloud cavitation by means of spectral proper orthogonal decomposition
Data-driven spatiotemporal analysis of cloud cavitation by means of spectral proper orthogonal decomposition Open
The global dynamics of cloud cavitation are not always obvious; cloud cavitation may exhibit chaotic, multimodal and intermittent behaviour, where dominant flow structures are hidden to the naked eye. To address this, spectral proper ortho…
View article: Data-driven spatiotemporal analysis of cloud cavitation by means of Spectral Proper Orthogonal Decomposition
Data-driven spatiotemporal analysis of cloud cavitation by means of Spectral Proper Orthogonal Decomposition Open
The global dynamics of cloud cavitation are not always obvious; cloud cavitation may exhibit chaotic, multimodal, and intermittent behaviour, where dominant flow structures are hidden to the naked eye. To address this, spectral proper orth…
View article: Iron oxide nanoparticle synthesis: Simulation-based comparison of laboratory- and pilot plant-scale spray-flame synthesis
Iron oxide nanoparticle synthesis: Simulation-based comparison of laboratory- and pilot plant-scale spray-flame synthesis Open
This study analyzes burner scale-dependent effects for iron-oxide nanoparticles synthesis in spray flames through a combined experimental and numerical approach. A laboratory- and a pilot plant-scale synthesis facility generate iron oxide …
View article: Development of a novel hydrogen-based burner concept for pilot-scale spray flame synthesis of nanoparticles
Development of a novel hydrogen-based burner concept for pilot-scale spray flame synthesis of nanoparticles Open
The development of a novel burner concept for the synthesis of nanoparticles in spray flames is described and the prototype is experimentally characterised. The burner was designed to enable the process to be scaled up while maintaining st…
View article: A hydrogen-based burner concept for pilot-scale spray-flame synthesis of nanoparticles: Investigation of flames and iron oxide product materials
A hydrogen-based burner concept for pilot-scale spray-flame synthesis of nanoparticles: Investigation of flames and iron oxide product materials Open
Nanoparticle synthesis in spray flames is a flexible method to produce materials with a wide range of compositions, morphologies, and properties. On the road to industrial application, the transfer from laboratory to pilot scale is an impo…
View article: Impact of runner crown shape modifications on the onset of the precessing vortex core
Impact of runner crown shape modifications on the onset of the precessing vortex core Open
In this experimental study, a passive flow control concept is provided to extend the stable part load operation regime by shifting the rise of the precessing vortex core (PVC), also known as vortex rope, toward lower mass flows respectivel…
View article: Identification of the precessing vortex core in a hydro turbine model using local stability analysis and stochastic modeling
Identification of the precessing vortex core in a hydro turbine model using local stability analysis and stochastic modeling Open
Stochastic modeling and local linear stability analysis (LSA) is employed to predict the onset of the precessing vortex core (PVC) in the hydro turbine model. The method of the stochastic modeling based on the pressure fluctuation signals …
View article: Mean flow data assimilation based on physics-informed neural networks
Mean flow data assimilation based on physics-informed neural networks Open
Physics-informed neural networks (PINNs) can be used to solve partial differential equations (PDEs) and identify hidden variables by incorporating the governing equations into neural network training. In this study, we apply PINNs to the a…
View article: Application of SPOD analysis to PIV data obtained in the wake of a circular cylinder undergoing vortex induced vibrations
Application of SPOD analysis to PIV data obtained in the wake of a circular cylinder undergoing vortex induced vibrations Open
Vortex induced vibrations (VIV) of a circular cylinder have been investigated experimentally using a cyberphysical apparatus with m∗ = 8, ζ = 0.005, and Re = 4000. This study considers the application of proper orthogonal decomposition (PO…
View article: Novel measurement system for respiratory aerosols and droplets in indoor environments
Novel measurement system for respiratory aerosols and droplets in indoor environments Open
The SARS-CoV-2 pandemic has created a great demand for a better understanding of the spread of viruses in indoor environments. A novel measurement system consisting of one portable aerosol-emitting mannequin (emitter) and a number of porta…
View article: Prediction of vortex precession in the draft tube of a model hydro turbine using mean field stability theory and stochastic modelling
Prediction of vortex precession in the draft tube of a model hydro turbine using mean field stability theory and stochastic modelling Open
In this work we employ mean field stability theory (MFST) to predict the onset of the precessing vortex core (PVC) in the draft tube of Francis turbines. MFST is based on the linear stability analysis of the mean field of turbulent flows. …
View article: Data-driven identification and modelling of coherent dynamics in turbulent flows
Data-driven identification and modelling of coherent dynamics in turbulent flows Open
This dissertation deals with methodological approaches for the titled identification and modelling of coherent dynamics in turbulent swirling jets. The identification concerns the development of a new method for the modal decomposition of …
View article: Identification of coherent structures in horizontal slug flow
Identification of coherent structures in horizontal slug flow Open
Multiphase flow measurement devices are significantly affected by the flow pattern, such as, e.g., slug flow, leading to large uncertainties. In this context, the slug flow pattern in horizontal pipes is investigated with the aim of findin…
View article: Anchoring of Turbulent Premixed Hydrogen/Air Flames at Externally Heated Walls
Anchoring of Turbulent Premixed Hydrogen/Air Flames at Externally Heated Walls Open
A joint experimental and numerical investigation of turbulent flame front anchoring at externally heated walls is presented. The phenomenon is examined for lean hydrogen/air mixtures in a novel burner design, which comprises a cylindrical …
View article: Single- and double-helix vortex breakdown as two dominant global modes in turbulent swirling jet flow
Single- and double-helix vortex breakdown as two dominant global modes in turbulent swirling jet flow Open
In this paper, we study the shape and dynamics of helical coherent structures found in the flow field of an annular swirling jet undergoing vortex breakdown. The flow field is studied by means of time-resolved tomographic particle image ve…
View article: On the nature of spectral proper orthogonal decomposition and related modal decompositions
On the nature of spectral proper orthogonal decomposition and related modal decompositions Open
The spectral proper orthogonal decomposition (SPOD) is a newly introduced extension of snapshot POD that recently gained attention but also brought up controversial issues. Within the first proposition, the approach was mainly presented in…
View article: Lagrangian coherent structures in the flow field of a fluidic oscillator
Lagrangian coherent structures in the flow field of a fluidic oscillator Open
This paper is associated with a video winner of a 2015 APS/DFD Gallery of Fluid Motion Award. The original video is available from the Gallery of Fluid Motion, http://dx.doi.org/10.1103/APS.DFD.2015.GFM.V0015
View article: Transient evolution of the global mode in turbulent swirling jets:\n experiments and modal stability analysis
Transient evolution of the global mode in turbulent swirling jets:\n experiments and modal stability analysis Open
Modal linear stability analysis has proven very successful in the analysis of\ncoherent structures of turbulent flows. Formally, it describes the evolution of\na disturbance in the limit of infinite time. In this work we apply modal linear…