The modern Huanghe River Delta is a representative hyper- pycnal-dominated delta in the world Li et al. In the considered case, an anti-kidney vortex is generated using two subsequent rows of holes both inclined downstream and yawed spanwise with alternating angles. A series of large-eddy simulations gives evidence that this deficiency may cause significant errors in important global quantities of the flow such as the mean wall shear stress. Within the nozzle, the flow is modeled by a potential flow core and a laminar, transitional, or developing turbulent boundary layer. Eddy Structures in a Simulated Plane Turbulent Jet Educed by Pattern Recognition Analysis; S. Direct Num erical Simulation of Transition in a Spatially Growing Compressible Boundary Layer Using a New Fourier Method; Y. Subgrid-Scale Models Based upon the Second-Order Structure-Function of Velocity; P.
Receptivity by Direct Numerical Simulation; G. It is split into inner and outer iteration cycles, such that the momentum and continuity equations are satisfied within prescribed accuracy. A strong antikidney vortex pair occurs for high momentum ratios I. No significant Reynolds-number effects are encountered in the present analysis which suggests that the findings may be generalized to flows at higher Reynolds numbers. A posteriori tests are performed for incompressible channel flow at two different Reynolds numbers.
This is a counter-rotating vortex pair, with an upward flow direction between the two vortices, which tends to lift off the surface and to locally feed hot air towards the blade outside the pair. The practical importance of turbulence led the U. A suspension drop is a swarm of particles that are suspended in initially still fluid. The influence of uniform suction across the wall on this bypass transition is investigated. This flow leads to a quasi-steady deflection of the cupula which increases until the driving forces of the steady streaming are balanced by the elastic reaction forces of the cupula, such that the cupula attains a constant deflection amplitude which lasts as long as the sound stimulus. The instantaneous flow features like the vorticity field are affected as well.
Direct Simulation of Breakdown to Turbulence following Oblique Instability Waves in a Supersonic Boundary Layer; N. The properties of the particulate plume in the freshwater current are analyzed as a function of the particle Stokes settling velocity. Further extensions consist of oblique impingement or different boundary suction directions, such as slip or stretching walls. This study extends our previous research on local linear stability of heated coaxial jetflows by analyzing the nonlinear evolution of initially laminar flows disturbed by a superposition of small-amplitude unstable eigenmodes. We demonstrate the effect of different windows with numerical simulation results for the far-field of a isothermal round jet.
The presence of two shear layers enables the interaction between otherwise free waves to give rise to new instabilities. The main focus is put on the modeling of turbulence coupling between the fluid and the particle phase. A priori Test of a Subgrid Scale Stress Tensor Model Including Anisotropy and Backscatter Effects; T. Very good agreement with reference data is obtained for the mean flow and turbulence profiles of both phases. It is demonstrated that disturbance amplitudes of less than 1% of the mean flow at, say, 10 step heights ahead of the step already suffice to produce a visibly three-dimensional structure of the separation zone. The asymptotic spreading of linear instabilities is investigated and its relation to the spot growth is discussed. Direct Num erical Simulation of Transition in a Spatially Growing Compressible Boundary Layer Using a New Fourier Method; Y.
Here, relatively cool air is ejected from a large isobaric plenum through an oblique round nozzle into a hotter turbulent boundary layer. Thereby, we hope to strongly modify the ow development and also al- ter the emitted near-acoustic eld. The problem lies not with our numerical approximations but with the size of the computational task and the complexity of the solutions we gen erate, which match the complexity of real turbulence precisely in so far as the computations mimic the real flows. While the flow inside the nozzle is very similar for the two cases, large differences occur in the mixing region, where a much enhanced spreading of the coolant is observed with the turbulent crossflow. A direct numerical simulation framework is developed and validated for investigating a jet-flow configuration in which a short cylindrical nozzle and the acoustic near field are included in the simulation domain. In the present contribution, an overview is given on recent advances with the simulation of transitional and turbulent incompressible wall-bounded shear flows. For computational efficiency, the temporal simulation approach has been adopted.
A brief comparison is also made to the jet sound field arising from a laminar nozzle-exit boundary layer. The rapid flow development in the changeover region from wall turbulence to the turbulent free shear layer within about one nozzle diameter is documented in detail. Published by the American Institute of Aeronautics and Astronautics, Inc. Generally our results are in good agreement with experimental as well as numerical data. The method allows to determine what kind of noise with respect to frequency and emission direction is generated at a given streamwise location.
Direct Num erical Simulation of Transition in a Spatially Growing Compressible Boundary Layer Using a New Fourier Method; Y. We present theoretical predictions for the streaming intensity which account for these new phenomena. For geometries that are more complex, but may still be decomposed into Cartesian subdomains, suitable domain decomposition methods are needed in order to apply fast diagonalization solvers. We analyze this problem on the basis of a spectral formulation of Lighthill's acoustic analogy and demonstrate that it can be understood as a problem of spectral leakage. The mixing behavior of the jet in crossflow is investigated by computing the evolution of a passive scalar. Large Eddy Simulation of Turbulent Boundary Layer Flow over a Hemisphere; M.