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We present a new approach for the Spectral Direct Numerical Simulation (DNS) of Low-Rm wall-bounded magnetohydrodynamic (MHD) flows. The novelty is that instead of using bases similar to the usual Chebyshev polynomials,
which are easy to implement but incur heavy computational costs to resolve the Hartmann boundary layers that arise along the
walls, we use a basis made of elements that already incorporate flow structures such as anisotropic vortices and Hartmann
layers. We show that such a basis can be obtained from the eigenvalue problem of the linear part of the governing equations
with the problem’s boundary conditions. Since this basis is not always orthogonal, we develop a spectral method for non-orthogonal
bases. We then demonstrate the efficiency of this method on the simple case of a laminar channel flow with periodic forcing.
In particular, we show that this method eliminates the computational costs incurred this Hartmann layer, and this for arbitrary high magnetic fields B. We then discuss the application of our method to nonlinear, turbulent flows for which the number of modes required to resolve
the flow completely decreases strongly when B increases, instead of increasing as in the case of currently employed Chebyshev-based methods. 相似文献
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R. Abela G. Backenstoss A.Brandao DOliveira M. Izycki H.O. Meyer I. Schwanner L. Tauscher P. Blüm W. Fetscher D. Gotta H. Koch H. Poth L.M. Simons 《Physics letters. [Part B]》1977,68(5):429-432
Pionic 3He atoms have been produced in a gaseous target. Energies and strong absorption broadening of the 2 → 1 and the 3 → 1 transition lines have been measured. The 1s level is shifted by 44 ± 5 eV by the (attractive) strong interaction, and the natural 1s level width is 42 ± 14 eV. 相似文献
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M. Izycki G. Backenstoss L. Tauscher P. Blüm R. Guigas N. Hassler H. Koch H. Poth B. Emmoth K. Fransson A. Nilsson P. Pavlopoulos K. Zioutas 《Zeitschrift für Physik A Hadrons and Nuclei》1980,297(1):1-9
The X-ray spectrum emerging from a liquid-hydrogen target when stopping antiprotons was measured with high resolution in order to determine the strong interaction shift and width of the atomic 1s level. Owing to strong Stark quenching only weak structures could be observed. The upper limit of the yield of any one of theK-series transitions is 3.5×10?4 (95% C.L.) per stopped antiproton, assuming no broadening of the 1s level. Possible identifications of the weak lines with theK-series transitions are discussed. 相似文献
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M. Izycki G. Backenstoss L. Tauscher P. Blüm R. Guigas N. Hassler H. Koch H. Poth K. Fransson A. Nilsson P. Pavlopoulos K. Zioutas 《Zeitschrift für Physik A Hadrons and Nuclei》1980,297(1):11-15
The X-ray spectrum associated withK ? stopping in liquid hydrogen was measured with high resolution Si(Li) detectors. The totalK X-ray yield is not larger than 8×10?4 per stoppedK ? assuming no line broadening. A weak line pattern was found, which was tentatively ascribed to theK ? HK-series X-rays. The shift and width of the 1s level, deduced from this pattern, are ε1s =+270±80 eV andΓ=560±260 eV, respectively. 相似文献
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A. Wolf H. Poth W. Schwab B. Seligmann M. Wörtge H. Haseroth C. E. Hill J. -L. Vallet 《Hyperfine Interactions》1989,44(1-4):217-232
The motivation of using electron cooling in low-energy antiproton storage rings and the expected cooling performance are discussed.
Results obtained recently, during the first operation of electron cooling in LEAR at CERN with a 50 MeV proton beam, are summarized,
concerning in particular the equilibrium beam properties, the recombination between cooling electrons and cooled protons,
and the deceleartion of acceleration of protons by friction in the electron beam. Conclusions are drawn for the formation
of antihydrogen with the cooled antiproton beam, and for the deceleration of antiprotons to energies close to or below 1 MeV. 相似文献