Shar Sajjadi

Embry-Riddle Aeronautical University · mathematics

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Topics (9) View all

Mathematics ×

278 Questions

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Applied Mathematics ×

86 Questions

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Numerical Modeling ×

26 Questions

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Turbulence ×

18 Questions

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Turbulence Modeling ×

4 Questions

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Hydrodynamic Stability ×

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Air-Sea Interactions ×

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theortical and computational fluid mechanics ×

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Questions and Answers (1) View all

Answer added in Turbulence
11 Do numerical solutions explain the origin of turbulence?
By Amador Muriel · Harvard University

Shar Sajjadi · Embry-Riddle Aeronautical University

Partially, yes. One can simulate laminar-transition-turbulence, in which the Tollmien-Schliching waves, as they appear at the onset of turbulence, ca... [more]

Partially, yes. One can simulate laminar-transition-turbulence, in which the Tollmien-Schliching waves, as they appear at the onset of turbulence, can be captured. Direct Numerical Simulation is a high resolution in space and particularly in time Navier-Stokes solver. The flaw with DNS is that any rough boundary cannot be incoporated in the simulation. This of course can augment or supress the near-wall turbulence.

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Publications (6) View all

Article: Numerical simulation of filamentation in laser-plasma interactions

D J Nicholas, S G Sajjadi

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ABSTRACT: Numerical studies of beam filamentation in laser-produced plasma are presented. This involves the numerical solution of the parabolic wave equation, known as the Schrodinger equation, coupled with the thermal transport equations for both ions and electrons, in two dimensions. The solution of the resulting equation with non-linear refractive index due to thermal and pondermotive forces, shows self-focusing and a variety of strong aberration effects. Intensity amplification at the final focus is found to be between one and two orders of magnitude greater than the initial beam intensity, governed in general by diffraction and aberration effects within the beam.

Journal of Physics D Applied Physics 11/2000; 19(5):737. · 2.54 Impact Factor
Article: The effect of light filamentation on uniformity of energy deposition in laser plasmas

D. J. Nicholas, S. G. Sajjadi

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ABSTRACT: The detailed behaviour of a beam of light propagating through a fully ionized plasma is studied near the critical density. Transient effects in the laser beam and plasma are included by taking into account, in a self-consistent manner, the proper motion of the plasma in an intense electromagnetic field. Parameters of the laser beam and plasma conditions are studied that prove most beneficial in providing a uniform deposition of energy. The behaviour of the light beams near the critical density at the three wavelengths 1054 nm, 527 nm and 351 nm are compared.

Journal of Plasma Physics 03/1989; 41(02):209 - 218. · 0.94 Impact Factor
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Available from: tudelft.nl

Article: Weak mean flows induced by anisotropic turbulence impinging onto planar and undulating surfaces

K. NAGATA, H. WONG, J. C. R. HUNT, S. G. SAJJADI, P. A. DAVIDSON

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ABSTRACT: Journal of Fluid Mechanics. v.556, 2006, p.329-360
Article: THRESHOLDS AND GROWTH OF INSTABILITY AND TURBULENCE IN FLUIDS AND PLASMAS

S G Sajjadi, D J Nicholas
Article: A STATISTICAL MECHANICS APPROACH TO THE INTERPRETATION OF TRANSITION FLOW

D J Nicholas, S G Sajjadi, T Chapman