Construction of a more complete quantum fluid model from Wigner-Boltzmann Equation with all higher order quantum corrections

A semiclassical Quantum Hydrodynamic model has been derived by taking the moments of the Wigner-Boltzmann equation. For the first time, the closure has been achieved by the use of the momentum shifted version of all order quantum corrected solution of the Wigner-Boltzmann equation and that has considerably extended the applicability of the model towards the low temperature and high density limit. In this context, the importance of the correlation and exchange effects have been retained through the Kohn-Sham equation in the construction of the Wigner-Boltzmann equation. The validity of the approach is subject to the existence of the Taylor's expansion of the associated Kohn-Sham potential.Comment: 10 page

Phase modulated solitary waves controlled by bottom boundary condition

A forced KdV equation is derived to describe weakly nonlinear, shallow water surface wave propagation over non trivial bottom boundary condition. We show that different functional forms of bottom boundary conditions self-consistently produce different forced kdV equations as the evolution equations for the free surface. Solitary wave solutions have been analytically obtained where phase gets modulated controlled by bottom boundary condition whereas amplitude remains constant.Comment: 13 pages, 6 figures, Accepted in Physical Review

Quantum corrections to nonlinear ion acoustic wave with Landau damping

Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to presence of Landau damping terms has been calculated assuming the Landau damping parameter $\alpha_1 = \sqrt{{m_e}/{m_i}}$ to be of the same order of the quantum parameter $Q = {\hbar^2}/({24 m^2 c^2_{s} L^2})$. The amplitude is shown to decay very slowly with time as determined by the quantum factor $Q$.Comment: 9 pages, 1 figur

Kelvin-Helmholtz Instability in non-Newtonian Complex Plasma

The Kelvin-Helmholtz (KH) instability is studied in a non-Newtonian dusty plasma with an experimentally verified model [Phys. Rev. Lett. {\bf 98}, 145003 (2007)] of shear flow rate dependent viscosity. The shear flow profile used here is a parabolic type bounded flow. Both the shear thinning and shear thickening properties are investigated in compressible as well as incompressible limits using a linear stability analysis. Like the stabilizing effect of compressibility on the KH instability, the non-Newtonian effect in shear thickening regime could also suppress the instability but on the contrary, shear thinning property enhances it. A detailed study is reported on the role of non-Newtonian effect on KH instability with conventional dust fluid equations using standard eigenvalue analysis.Comment: 13 pages, 4 figure

Bending of solitons in weak and slowly varying inhomogeneous plasma

Bending of solitons in two dimensional plane is presented in the presence of weak and slowly varying inhomogeneous ion density for the propagation of ion acoustic soliton in unmagnetized cold plasma with isothermal electrons. Using reductive perturbation technique, a modified Kadomtsev- Petviashvili equation is obtained with a chosen unperturbed ion density profile. Exact solution of the equation shows that the phase of the solitary wave gets modified by a function related to the unperturbed inhomogeneous ion density causing the soliton to bend in the two dimensional plane, whereas the amplitude of the soliton remaining constantComment: 10 pages, 11 figure

Jeans Instability in a viscoelastic fluid

The well known Jeans instability is studied for a viscoelastic, gravitational fluid using generalized hydrodynamic equations of motions. It is found that the threshold for the onset of instability appears at higher wavelengths in a viscoelastic medium. Elastic effects playing a role similar to thermal pressure are found to lower the growth rate of the gravitational instability. Such features may manifest themselves in matter constituting dense astrophysical objects.Comment: 10 pages, 4 figure

A new (2+1) dimensional integrable evolution equation for an ion acoustic wave in a magnetized plasma

A new, completely integrable, two dimensional evolution equation is derived for an ion acoustic wave propagating in a magnetized, collisionless plasma. The equation is a multidimensional generalization of a modulated wavepacket with weak transverse propagation, which has resemblance to nonlinear Schrodinger (NLS) equation and has a connection to Kadomtsev-Petviashvili equation through a constraint relation. Higher soliton solutions of the equation are derived through Hirota bili- nearization procedure, and an exact lump solution is calculated exhibiting 2D structure. Some mathe- matical properties demonstrating the completely integrable nature of this equation are described. Modulational instability using nonlinear frequency correction is derived, and the corresponding growth rate is calculated, which shows the directional asymmetry of the system. The discovery of this novel (2{\th}1) dimensional integrable NLS type equation for a magnetized plasma should pave a new direction of research in the field.Comment: 11 pages, 8 figure

Controlling near shore nonlinear surging waves through bottom boundary conditions

Instead of taking the usual passive view for warning of near shore surging waves including extreme waves like tsunamis, we aim to study the possibility of intervening and controlling nonlinear surface waves through the feedback boundary effect at the bottom. It has been shown through analytic result that the controlled leakage at the bottom may regulate the surface solitary wave amplitude opposing the hazardous variable depth effect. The theoretical results are applied to a real coastal bathymetry in India.Comment: 19 pages, 12 figure

Shear Waves in an inhomogeneous strongly coupled dusty plasma

The properties of electrostatic transverse shear waves propagating in a strongly coupled dusty plasma with an equilibrium density gradient are examined using the generalized hydrodynamic equation. In the usual kinetic limit, the resulting equation has similarity to zero energy Schrodinger's equation. This has helped in obtaining some exact eigenmode solutions in both cartesian and cylindrical geometries for certain nontrivial density profiles. The corresponding velocity profiles and the discrete eigenfrequencies are obtained for several interesting situations and their physics discussed.Comment: 10 pages, 4 figure

Viscosity gradient driven instability of `shear mode' in a strongly coupled plasma

The influence of viscosity gradient (due to shear flow) on low frequency collective modes in strongly coupled dusty plasma is analyzed. It is shown that for a well known viscoelastic plasma model, the velocity shear dependent viscosity leads to an instability of the shear mode. The inhomogeneous viscous force and velocity shear coupling supply the free energy for the instability. The combined strength of shear flow and viscosity gradient wins over any stabilizing force and makes the shear mode unstable. Implication of such a novel instability and its applications are briefly outlined.Comment: 9 pages, 2 figure