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Recent investigations of laminar flow control for swept-wing boundary-layer flows provide promising results with respect to crossflow-transition delay using a technique called pinpoint suction. Strong, localized suction through holes accurately positioned with respect to the crossflow-vortex position can directly weaken the growth of secondary instabilities that are responsible for the final laminar...
Direct numerical simulations (DNS) of stably-stratified, turbulent plane Couette flow are currently being performed on the XC-4000. The friction Reynolds number is kept approximately constant, Reτ≃540 and the Richardson number Riw varies between 0 and 0.1. The flow is divided into two regions: the region close to the wall and...
From experimental studies it is well established that free-stream and wake-induced turbulence can increase the heat transfer on curved surfaces such as turbine blades or cylinders even if the mean flow matches corresponding laminar velocity profiles. Here, preliminary results of an investigation using (embedded) Direct Numerical Simulation (DNS) are reported that aim at identifying the responsible...
The application of a novel turbulent inflow generator is presented using a 3D Direct Numerical Simulation (DNS) method. For simulation the in-house 3D CFD program Free Surface 3D (FS3D) is applied, which solves the incompressible Navier Stokes Equations for flows with free surfaces using a Volume-of-Fluid (VOF) technique. Three different numerical setups are presented, demonstrating the wide range...
In the present paper a high pressure emulsification process in a homogenizing orifice is investigated. Contrary to former published papers no turbulence model is applied to calculate the turbulent and quasiturbulent effects, but a direct numerical simulation is carried out. Especially in narrow gaps turbulence models are not valid, hence important effects are damped out. In the wake of the orifice...
Direct numerical simulations of interface-resolved sediment transport in horizontal open-channel flow are currently being performed on the XC-4000. The channel bottom boundary is roughened with a fixed layer of spheres and about 9000 particles are allowed to move within the computational domain. The density ratio of the solid and fluid phase is 1.7 and the bulk Reynolds number of the flow is 2880...
Impinging jets are used in a variety of engineering applications like in chemical reactors, mixing devices, drying and cooling applications. Good quality simulations of this highly complex flow field is a challenging task. In this work, the flow field and heat transfer of turbulent jet impingement is investigated by Large Eddy Simulation (LES). The benchmark case of a turbulent impinging jet with...
The suitability of Large Eddy Simulations to study the jet in crossflow configuration under high turbulent conditions was investigated. The simulations were conducted using a solver programmed with the open source OpenFOAM CFD Toolbox. The grid dependence of the results was studied. While only small differences are visible in the mean variables, the turbulence description is affected by the grid resolution,...
In rectangular ducts with fully-developed turbulent flow, mean vortices in the corners form secondary flow patterns whose energy contents is orders of magnitude lower than that of the flow in the streamwise direction. In the present numerical experiments, it is demonstrated using Large Eddy Simulations (LES) that these Mean Secondary Vortices (MSV) exert a profound influence on flow separation in...
In the literature, numerical computations of the Czochralski process for crystal growth are conducted using a quasi-steady state assumption for the crystallization neglecting time-dependent effects. In the present work, an algorithm is developed, which allows to calculate the transient behavior of the crystallization interface including the movement of the three-phase boundary and the free surface...
In this paper a zonal RANS/LES approach is presented in which the regions with attached boundary-layers are computed via RANS and the regions with separated flows by using LES. The transition from RANS to LES takes place in an overlapping region between the RANS and LES zone. Two different turbulent inflow generation methods coupled with a controlled forcing ansatz are applied which enable a fast...
A Large-Eddy Simulation of several cycles of a spark-ignition engine with port fuel injection has been performed. The investigated engine is a modified Rotax-engine with one cylinder and four valves, built and measured (Heidenreich, Private communication) by the Institute of Reciprocating Engines of the University of Karlsruhe (IFKM). A recently modified (Magagnato et al., 2008) progress variable...
Demands concerning geometrical detail arising in the simulation of certain flow phenomena in helicopter interactional aerodynamics can only be dealt with in an unstructured simulation environment. This work deals with the extension of the simulation capabilities at IAG to an unstructured flow solver. The new approach is validated against and compared to the standard structured flow chain in the context...
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