Herbert Oertel’s research while affiliated with University of Oxford and other places

... This paper addresses the traceability and reversibility of anonymized metric data or target values through discretization, which may lead to security or information loss. Techniques such as ordinalization [8] and rounding [9] coarsen the metric space into Stats 2024, 7 1190 adjacent ordinal classes, leading to information loss depending on the number of ordinal classes. Previous research has explored the evaluation of data based on discrete classes, considering the uncertainty of data [10], the optimum between data usability and maximum anonymity [11], and data diversity and characteristic details [12]. ...

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Is Anonymization Through Discretization Reliable? Modeling Latent Probability Distributions for Ordinal Data as a Solution to the Small Sample Size Problem

... Für den Druckauslass in der Fanebene wurde eine Machzahl Ma 2 von 0,5 gewählt [8], [11], [47]. Mit Hilfe der idealen Gasgleichung und der Bernoulli-Gleichung wurden die verbleibenden Randbedingungen ermittelt und mit der Fachliteratur abgeglichen [10], [338], [339], vgl. Wöllner [315, S. 45-64] und Tabelle A.5 in Anhang A.5. ...

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Variable Pitot-Triebwerkseinlässe für kommerzielle Überschallflugzeuge. Konzeptstudie mittels eines Entwicklungsansatzes für sichere Produkte

... Low Reynolds number turbulence models require a finer discretization of the near-wall region, since the logarithmic wall function, which is used to describe the behaviour of the flow near to the wall in the standard k-ε model, is only applicable for highly turbulent flows. Additionally, modifications of the equation for the turbulent kinetic energy k are necessary [223]. Especially for the simulation of wood log stoves, the usage of a low Reynolds number k-ε model should be considered. ...

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Review on modelling approaches based on computational fluid dynamics for biomass combustion systems

... [9,44] There are numerous physical and geometrical factors that contribute to the heat transfer of impinging jet flows. The most important physical factors are expressed by the nondimensional quantities Re, P r and the Mach number M a. M a is defined by the flow velocity u and the speed of sound a, which is computed using the heat capacity ratio κ, the gas constant R and the temperature T [32]. ...

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Large Eddy Simulation of a Generic Impinging Jet Configuration

... Translated to the DynaMiTES, with a donor volume of 370 µL, the initial volume flow is set to 1.22 µL·s -1 first and reduced to 0.52 µL·s -1 to simulate the basal phase. Under laminar flow conditions, the shear stress τ [Pa] at the membrane surface depends on the volume flow inside the donor microchannel V [m³·s -1 ] as τ 3η/(2A cs ·hc) [15], where η [Pa·s] is the viscosity of the fluid, h c [m] the height of the donor microchannel, and A cs [m²] the area of the channel cross section [15]. ...

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DynaMiTES - A dynamic cell culture platform for in vitro drug testing PART 1 - Engineering of microfluidic system and technical simulations

... Another fundamental issue that needs to be addressed is hemocompatibility: pump thrombosis and its related adverse events (strokes, systemic embolisms) remains the Achilles heel of BMCS despite aggressive antiacoagulant and antiplatelet therapies which may furthermore cause gastrointestinal or cerebral bleeding. Consequently, in order to mitigate the phenomena of thrombosis, future MCS devices must focus their attention on improving the design of pump geometry, the materials, and the blood-contacting surfaces (52). In this optic, a new pumping concept-the so-called progressive wave pump-is under study: it consists in the interaction of an elastic membrane actuated by forced excitation with a surrounding fluid and the pump housing which is expected to reduce blood trauma, to increase hydraulic performance, and perhaps to require lower levels of anticoagulation (53). ...

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Current and future options for adult biventricular assistance: a review of literature

... The shape of the back side of the bluff body strongly affects the vortex size, its strength and the frequency of vortex shedding. The flow behind different body shapes has been investigated by several authors [10], [23], [45], [46]. In terms of vortex strength, flow A should be strong, flow C should be weak and entrainment flow B should be sufficiently high to allow the vortex to detach. ...

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Experimental verification and numerical simulation of a vortex flowmeter at low Reynolds numbers

... This also minimizes the risk of developing a thrombus. Both simulation results show the same flow-structure behavior as shown by Krittian et al. 8 New characteristic FSI numbers have been derived in order to capture the fluid-structure interaction effects quantitatively. First evaluation processes showed the interplay of flow energy, diffusion and acceleration with the structural deformation. ...

Reference:

Partitioned Fluid–Solid Coupling for Cardiovascular Blood Flow

... development [3,22,6], aquatic locomotion [19,2,12], and animal flight [27,31,20] to organismal feeding and filtering [17,28,33] and beyond. ...

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Fluid-Structure Interaction for the Classroom: Interpolation, Hearts, and Swimming!

... Degradation in grid quality due to the large structural deformation is mitigated through the implementation of grid smoothing and remeshing strategies. Using this method, idealized LV models simulating ventricular motion via temporally varying the myocardial Young's modulus [125], [126] and whole heart models implementing sophisticated electrophysical FSI models [127], [128] have been developed and used to characterize realistic hemodynamics. Separation of the fluid domain through surface-to-surface contact is impossible to numerically resolve, unfortunately, hampering efforts to accurately characterize heart valve coaptation [129]. ...

Reference:

Unraveling the Etiologies of Discrete Subaortic Stenosis: A Focus on Left Ventricular Outflow Tract Hemodynamics