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2002 - 200932010 - 20151
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Scopus Q: Q2 × Konu: Propagation ×

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Listeleniyor 1 - 4 / 4
  • Küçük Resim
    Yayın
    Modulation of electron-acoustic waves in a plasma with vortex electron distribution
    (Walter De Gruyter GMBH, 2015-04) Demiray, Hilmi
    In the present work, employing a one-dimensional model of a plasma composed of a cold electron fluid, hot electrons obeying a trapped/vortex-like distribution and stationary ions, we study the amplitude modulation of electron-acoustic waves by use of the conventional reductive perturbation method. Employing the field equations with fractional power type of nonlinearity, we obtained the nonlinear Schrodinger equation as the evolution equation of the same order of nonlinearity. Seeking a harmonic wave solution with progressive wave amplitude to the evolution equation it is found that the NLS equation with fractional power assumes envelope type of solitary waves.
  • Küçük Resim
    Yayın
    Amplitude modulation of nonlinear waves in a fluid-filled tapered elastic tube
    (Wiley-V C H Verlag, 2003) Demiray, Hilmi
    In the present work, treating the arteries as a tapered, thin walled, long, and circularly conical prestressed elastic tube and using the reductive perturbation method, we have studied the amplitude modulation of nonlinear waves in such a fluid-filled elastic tube. By considering the blood as an incompressible non-viscous fluid, the evolution equation is obtained as the nonlinear Schrodinger equation with variable coefficients. It is shown that this type of equations admit a solitary wave type of solution with a variable wave speed. It is observed that the wave speed increases with distance for narrowing tubes while it decreases for expanding tubes.
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    Waves in fluid-filled elastic tubes with a stenosis: Variable coefficients KdV equations
    (Elsevier B.V., 2007-05-15) Demiray, Hilmi
    In the present work, by treating the arteries as thin-walled prestressed elastic tubes with a stenosis and the blood as an inviscid fluid we have studied the propagation of weakly nonlinear waves in such a medium, in the longwave approximation, by employing the reductive perturbation method. The variable coefficients KdV and modified KdV equations are obtained depending on the balance between the nonlinearity and the dispersion. By seeking a localized progressive wave type of solution to these evolution equations, we observed that the wave speeds takes their maximum values at the center of stenosis and gets smaller and smaller as one goes away from the stenosis. Such a result seems to reasonable from the physical point of view.
  • Küçük Resim
    Yayın
    Weakly nonlinear waves in elastic tubes filled with a layered fluid
    (Freund Publishing House, 2002) Demiray, Hilmi
    In this work we studied the propagation of weakly nonlinear waves in a prestressed thin elastic tube filled with an incompressible layered fluid, where the outer layer is assumed to be inviscid whereas the cylindrical core is considered to be viscous. Using the reductive perturbation technique, the propagation of weakly nonlinear waves in the longwave approximation is studied. The governing equation is shown to be the Korteweg-de Vries-Burgers' equation. A travelling wave type of solution for this evolution equation is sought and it is shown that with increasing core radius parameter the formation of strong shock wave becomes inevitable.