Gas turbines. Compressible flow. Finite volume method. Flow structure. Turbulent flow. Deville, T-H. Sagaut Eds. Shimada, Y.
Compressible Turbulence in Interactions of Supersonic Flows
A fifth-order accurate methods was used to achieve high order spatial accuracy and a second order explicit scheme was applied for time integration. Comparison of mean and fluctuating velocity components and mixture fraction with experiment and conventional LES demonstrated that the ILES successfully captured the turbulent flow structures without explicit subgrid scale modelling. Large eddy simulation of turbulent jet flow in gas turbine combustors.
N2 - Implicit Large Eddy Simulation ILES in conjunction with high resolution and high order computational modelling was applied to a turbulent mixing jet of a fuel injector in gas turbine combustors. AB - Implicit Large Eddy Simulation ILES in conjunction with high resolution and high order computational modelling was applied to a turbulent mixing jet of a fuel injector in gas turbine combustors.
Department of Engineering. Abstract Implicit Large Eddy Simulation ILES in conjunction with high resolution and high order computational modelling was applied to a turbulent mixing jet of a fuel injector in gas turbine combustors. Fingerprint Large eddy simulation. Such an Alfvenicity reduction was seen in solar wind observations [ Roberts et al. In the first panel of Figure 13 the superposed average of the Alfvenicity A of the solar wind plasma is plotted as the black curves, the thin curve with 1 h resolution and the thick curve being a 7 h running average. As can be seen, there is no statistically significant decrease in the Alfvenicity coincident with the shear at the stream interface.
To summarize, in this examination of the Alfvenic correlations no evidence is found for the driving of turbulence by shear. If turbulence is being driven by shear at the stream interface and if the energy of spectral transfer goes into ion heating [cf.
Smith et al.
This signature appears to be a transition of the specific entropy between the slow wind and the fast wind, not a signature of turbulent heating at the stream interface. To summarize, in this examination of the specific entropy no evidence for the driving of turbulence by shear is found.
The chief findings are numbered for clarity. The zero epoch for each CIR was taken to be the CIR stream interface as determined by the maximum in the plasma vorticity. A few properties of the plasma and turbulence exhibit smooth transitions in properties from the slow wind to the fast wind across the entire CIR: these are the amplitudes and normalized amplitudes of the velocity fluctuations and the magnetic field fluctuations.
The amplitude of the velocity and magnetic field fluctuations with and without discontinuities in the analysis is low in the slow wind, is high in the fast wind, and makes a smooth transition between the two levels across the CIR. The Alfven ratio has similar values in the slow and fast wind: the Alfven ratio is about 0. At the stream interface a sharp decrease in the Alfven ratio is seen, indicating considerably more energy in magnetic field fluctuations than in velocity fluctuations.
The Alfvenicity of the solar wind plasma is observed to smoothly vary from low positive values to higher positive values across the CIR from the slow wind to the fast wind.
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The degree of correlations between the velocity fluctuations and the magnetic field fluctuations, as measured by the absolute value of the Alfvenicity, increases smoothly across the CIR from low values in the slow wind to higher values in the fast wind. The Alfvenicity and the degree of correlation is higher in all locations for discontinuities in the solar wind than for the solar wind plasma in general. The magnetic field spectral index is slightly shallower in the fast wind than it is in the slow wind. The amplitude of the inward fluctuations is similar in the slow wind and in the fast wind: the amplitude of the outward fluctuations is much higher in the fast wind than in the slow wind.
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The spectral slopes of the inward propagating and outward propagating Elsasser variables are similar in the slow wind and in the CIR, but the spectral slope of the inward propagating variable becomes steep in the fast wind. The amount of spreading of turbulence across the magnetic field in the lifetime of the solar wind plasma is limited.
The limit on the spreading implies that any turbulence observed will be localized around the site where it is driven. No such evidence was found. This would provide information about the temporal evolution of turbulence under shear as compared with the temporal evolution of the unsheared solar wind. This would provide an improvement to the methodology of section 5. And finally, an understanding of why the velocity and magnetic field spectra in the solar wind differ is needed before a full understanding of MHD turbulence can be claimed.
Measurements in turbulent boundary layers find turbulence correlation lengths normal to the shear and spanwise to be about the width of the boundary layer [ Kovasznay et al. Measurements in Couette flow [ Vaezi et al. Similar results are found for measurements [ Bailey et al. This is consistent with some of the correlation lengths measured in the solar wind [e. Starting from the integral scale k o , the Kolmogorov cascade will propagate to infinitely higher k in a time scale that is 2.
The factor 2.
Nonlinear waves and turbulence in space plasmas contributions
Hence the Kraichnan spectrum will fully develop in 3. Taking 2. For instance, at 0. Hundhausen , , Figure 4]. With the velocity change preserved and the width of the shear zone decreased by a factor of approximately 0. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries other than missing content should be directed to the corresponding author for the article.
Volume , Issue A If you do not receive an email within 10 minutes, your email address may not be registered, and you may need to create a new Wiley Online Library account. If the address matches an existing account you will receive an email with instructions to retrieve your username. Open access. Solar and Heliospheric Physics Free Access. Joseph E. Borovsky E-mail address: jborovsky lanl.
Michael H. Tools Request permission Export citation Add to favorites Track citation. Share Give access Share full text access. Share full text access. Please review our Terms and Conditions of Use and check box below to share full-text version of article. Introduction  Turbulence in a magnetized plasma is characterized by a spectrum of velocity fluctuations and of magnetic field fluctuations that both have a large range of time scales and length scales. Figure 1 Open in figure viewer PowerPoint. An idealized sketch of a corotating interaction region CIR in the equatorial plane.
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The CIR is shaded in gray with the stream interface denoted as the black curve. Figure 2 Open in figure viewer PowerPoint. In Figure 2 middle and bottom the 25th and 75th percentiles of the specific entropy are plotted as red curves. Figure 3 Open in figure viewer PowerPoint. Overview of CIR Structure  In Figure 4 the averaged flow velocities and plasma parameters of the solar wind are plotted as a function of time for a superposition of the 27 CIRs of Table 1.