Download or read book Numerical Simulation of a Plane Wake written by Socrates G. Potamitis and published by . This book was released on 1992 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation of a Temporally Evolving Incompressible Plane Wake Effect of Initial Conditions on Evolution and Topology written by R. Sondergaard and published by . This book was released on 1997 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vortex wakes of Aircrafts written by A.S. Ginevsky and published by Springer Science & Business Media. This book was released on 2009-07-07 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigation of vortex wakes behind various aircraft, especially behind wide bodied and heavy cargo ones, is of both scientific and practical in terest. The vortex wakes shed from the wing’s trailing edge are long lived and attenuate only atdistances of10–12kmbehindthe wake generating aircraft. The encounter of other aircraft with the vortex wake of a heavy aircraft is open to catastrophic hazards. For example, air refueling is adangerous operationpartly due to thepossibility of the receiver aircraft’s encountering the trailing wake of the tanker aircraft. It is very important to know the behavior of vortex wakes of aircraft during theirtakeoff andlanding operations whenthe wakes canpropagate over the airport’s ground surface and be a serious hazard to other depart ing or arriving aircraft. This knowledge can help in enhancing safety of aircraft’s movements in the terminal areas of congested airports where the threat of vortex encounters limits passenger throughput. Theoreticalinvestigations of aircraft vortex wakes arebeingintensively performedinthe major aviationnations.Usedforthispurpose are various methods for mathematical modeling of turbulent flows: direct numerical simulation based on the Navier–Stokes equations, large eddy simulation using the Navier–Stokes equations in combination with subrigid scale modeling, simulation based on the Reynolds equations closed with a differential turbulence model. These approaches are widely used in works of Russian and other countries’ scientists. It should be emphasized that the experiments in wind tunnels and studies of natural vortex wakes behind heavy and light aircraft in flight experiments are equally important.
Download or read book Direct Numerical Simulation of a Temporally Evolving Incompressible Plane Wake written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-24 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct numerical simulations have been used to examine the effect of the initial disturbance field on the development of three-dimensionality and the transition to turbulence in the incompressible plane wake. The simulations were performed using a new numerical method for solving the time-dependent, three-dimensional, incompressible Navier-Stokes equations in flows with one infinite and two periodic directions. The method uses standard Fast Fourier Transforms and is applicable to cases where the vorticity field is compact in the infinite direction. Initial disturbances fields examined were combinations of two-dimensional waves and symmetric pairs of 60 deg oblique waves at the fundamental, subharmonic, and sub-subharmonic wavelengths. The results of these simulations indicate that the presence of 60 deg disturbances at the subharmonic streamwise wavelength results in the development of strong coherent three-dimensional structures. The resulting strong three-dimensional rate-of-strain triggers the growth of intense fine scale motions. Wakes initiated with 60 deg disturbances at the fundamental streamwise wavelength develop weak coherent streamwise structures, and do not develop significant fine scale motions, even at high Reynolds numbers. The wakes which develop strong three-dimensional structures exhibit growth rates on par with experimentally observed turbulent plane wakes. Wakes which develop only weak three-dimensional structures exhibit significantly lower late time growth rates. Preliminary studies of wakes initiated with an oblique fundamental and a two-dimensional subharmonic, which develop asymmetric coherent oblique structures at the subharmonic wavelength, indicate that significant fine scale motions only develop if the resulting oblique structures are above an angle of approximately 45 deg. Sondergaard, R. and Cantwell, B. and Mansour, N. Ames Research Center NASA-CR-203613, NAS 1.26:203613, JIAA-TR-118 NCC2-55; N00014-90-J-1976...
Download or read book Direct Numerical Simulation of a Temporally Evolving Incompressible Plane Wake written by Rolf Sondergaard and published by . This book was released on 1995 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulations of a Plane Compressible Wake written by Jacqueline H. Chen and published by . This book was released on 1898 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulations of a Plane Compressible Wake written by Jacqueline H. Chen and published by . This book was released on 1989 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Method for Approximating the Initial Data Plane for Surface Ship Wake Simulations written by and published by . This book was released on 1988 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: For some time, remotely sensed data of the ocean surface have been used to determine surface conditions. It was clear that ship wake features could be readily identified in the remotely sensed data. The recent SIR/B series of synthetic aperture radar experiments were analyzed and clearly showed that surface vessels can be located by wake detection and that it may be possible to classify ship types by certain wake characteristics. As a result of these and other observations, the hydrodynamic characteristics of surface ship wakes have been of growing interest. A procedure for obtaining a set of near wake initial condition data for the parabolic numerical simulation of the turbulent far wake of a surface ship is developed. The principal elements of a surface ship wake are considered and are modeled based on experimental data. The wakes of the individual elements are assembled using linear superposition. Interactions among elements are discussed but not modelled. The superposition procedure is implemented in a computer code which uses parameters of the ship as program input. Results generated by the code for a guided missile destroyer model are presented and compared with limited experimental data. Keywords: Parabolic Navier-Stokes equations; Numerical simulations; Initial data plane.
Download or read book Numerical Simulation of a Planar Turbulent Wake in Arbitrary Pressure Gradient written by Gregory P. Brooks and published by . This book was released on 1999 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Evaluation of the Measurement Requirements for an In Situ Wake Vortex Detection System written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-30 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of a numerical simulation are presented to determine the feasibility of estimating the location and strength of a wake vortex from imperfect in-situ measurements. These estimates could be used to provide information to a pilot on how to avoid a hazardous wake vortex encounter. An iterative algorithm based on the method of secants was used to solve the four simultaneous equations describing the two-dimensional flow field around a pair of parallel counter-rotating vortices of equal and constant strength. The flow field information used by the algorithm could be derived from measurements from flow angle sensors mounted on the wing-tip of the detecting aircraft and an inertial navigation system. The study determined the propagated errors in the estimated location and strength of the vortex which resulted from random errors added to theoretically perfect measurements. The results are summarized in a series of charts and a table which make it possible to estimate these propagated errors for many practical situations. The situations include several generator-detector airplane combinations, different distances between the vortex and the detector airplane, as well as different levels of total measurement error. Fuhrmann, Henri D. and Stewart, Eric C. Langley Research Center RTOP 505-69-59-04...
Download or read book 3D Visualization of Unsteady 2D Airplane Wake Vortices written by Kwan-Liu Ma and published by . This book was released on 1994 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "Air flowing around the wing tips of an airplane forms horizontal tornado-like vortices that can be dangerous to following aircraft. The dynamics of such vortices, including ground and atmospheric effects, can be predicted by numerical simulation, allowing the safety and capacity of airports to be improved. In this paper, we introduce three-dimensional techniques for visualizing time-dependent, two-dimensional wake vortex computations, and the hazard strength of such vortices near the ground. We describe a vortex core tracing algorithm and a local tiling method to visualize the vortex evolution. The tiling method converts time-dependent, two-dimensional vortex cores into three-dimensional vortex tubes. Finally, a novel approach calculates the induced rolling moment on the following airplane at each grid point within a region near the vortex tubes and thus allows three-dimensional visualization of the hazard strength of the vortices. We also suggest ways of combining multiple visualization methods to present more information simultaneously."
Download or read book Numerical Experiments in Homogeneous Turbulence written by Robert Sugden Rogallo and published by . This book was released on 1981 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct numerical simulation of weakly stratified turbulent wake written by T. S. Lund and published by . This book was released on 2014 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulation of Unsteady Flows and Transition to Turbulence written by O. Pironneau and published by Cambridge University Press. This book was released on 1992-07-31 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: The workshop concentrated on the following turbulence test cases: T1 Boundary layer in an S-shaped duct; T2 Periodic array of cylinders in a channel; T3 Transition in a boundary layer under the influence of free-stream turbulence; T4 & T5: Axisymmetric confined jet flows.
Download or read book Numerical Modeling Studies of Wake Vortices written by Shaohua Shen and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulation of the Tip Vortex Off a Low aspect ratio Wing at Transonic Speed written by and published by . This book was released on 1984 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
