Bifurcations and exact solutions for a nonlinear surface wind waves equation

PurposeThis paper aims to solve linear and non-linear shallow water wave equations using homotopy perturbation method (HPM). HPM is a straightforward method to handle linear and non-linear differential equations. As such here, one-dimensional shallow water wave equations have been considered to solve those by HPM. Interesting results are reported when the solutions of linear and non-linear equations are compared.Design/methodology/approachHPM was used in this study.FindingsSolution of one-dimensional linear and non-linear shallow water wave equations and comparison of linear and non-linear coupled shallow water waves from the results obtained using present method.Originality/valueCoupled non-linear shallow water wave equations are solved.

Chapter 7 On the Global Weak Solutions to a Variational Wave Equation

The exact parametric representations of the traveling wave solutions for a nonlinear elastic rod equation are considered. By using the method of planar dynamical systems, in different parameter regions, the phase portraits of the corresponding traveling wave system are given. Exact explicit kink wave solutions, periodic wave solutions and some unbounded wave solutions are obtained.

A corrected derivation of nonlinear wave propagation equations with fractional loss operators is presented. The fundamental approach is based on fractional formulations of the stress-strain and heat flux definitions but uses the energy equation and thermodynamic identities to link density and pressure instead of an erroneous fractional form of the entropy equation as done in Prieur and Holm ["Nonlinear acoustic wave equations with fractional loss operators," J. Acoust. Soc. Am. 130(3), 1125-1132 (2011)]. The loss operator of the obtained nonlinear wave equations differs from the previous derivations as well as the dispersion equation, but when approximating for low frequencies the expressions for the frequency dependent attenuation and velocity dispersion remain unchanged.

Invariant subspaces, exact solutions and stability analysis of nonlinear water wave equations

This paper is concerned with the lifespan of and the blowup mechanism for smooth solutions to the 2-D nonlinear wave equation ∂ t 2 u − ∑ i = 1 2 ∂ i ( c i 2 ( u ) ∂ i u ) \partial _t^2u-\sum _{i=1}^2\partial _i(c_i^2(u)\partial _iu) = 0 =0 , where c i ( u ) ∈ C ∞ ( R n ) c_i(u)\in C^{\infty }(\mathbb {R}^n) , c i ( 0 ) ≠ 0 c_i(0)\neq 0 , and ( c 1 ′ ( 0 ) ) 2 + ( c 2 ′ ( 0 ) ) 2 ≠ 0 (c_1’(0))^2+(c_2’(0))^2\neq 0 . This equation has an interesting physical background as it arises from the pressure-gradient model in compressible fluid dynamics and also in nonlinear variational wave equations. Under the initial condition ( u ( 0 , x ) , ∂ t u ( 0 , x ) ) = ( ε u 0 ( x ) , ε u 1 ( x ) ) (u(0,x), \partial _tu(0,x))=(\varepsilon u_0(x), \varepsilon u_1(x)) with u 0 ( x ) , u 1 ( x ) ∈ C 0 ∞ ( R 2 ) u_0(x), u_1(x)\in C_0^{\infty }(\mathbb {R}^2) , and ε > 0 \varepsilon >0 is small, we will show that the classical solution u ( t , x ) u(t,x) stops to be smooth at some finite time T ε T_{\varepsilon } . Moreover, blowup occurs due to the formation of a singularity of the first-order derivatives ∇ t , x u ( t , x ) \nabla _{t,x}u(t,x) , while u ( t , x ) u(t,x) itself is continuous up to the blowup time T ε T_{\varepsilon } .

We discuss two classes of solutions to a novel Casimir equation associated with the Ito system, a coupled nonlinear wave equation. Both travelling wave solutions and separable self-similar solutions are discussed. In a number of cases, explicit exact solutions are found. Such results, particularly the exact solutions, are useful in that they provide us a baseline of comparison to any numerical simulations. Besides, such solutions provide us a glimpse of the behavior of the Ito system, and hence the behavior of a type of nonlinear wave equation, for certain parameter regimes.

Generalization of the algebraic method of group classification with application to nonlinear wave and elliptic equations

Conservation laws and non-invariant solutions of anisotropic wave equations with a source

This paper is concerned with a class of nonlinear stochastic wave\nequations in $\\mathbb{R}^d$ with $d \\leq 3$, for which the nonlinear terms are\npolynomial of degree $m$. As an example of the nonexistence of a global\nsolution in general, it is shown that there exists an explosive solution of\nsome cubically nonlinear wave equation with a noise term. Then the existence\nand uniqueness theorems for local and global solutions in Sobolev space $H_1$\nare proven with the degree of polynomial $m \\leq 3$ for $d = 3$, and $m \\geq 2$\nfor $d = 1$ or 2.

Nonlinear waves in a liquid containing gas bubbles are considered in the three-dimensional (3D) case. The nonlinear evolution equation is given for a description of long nonlinear pressure waves. It is shown that in the general case the equation is not integrable. Some exact solutions for the nonlinear evolution equation are presented. The application of the Hirota method is illustrated for finding multi-soliton solutions for the nonintegrable evolution equation in the 3D case. The stability of the 1D solitary waves is investigated. It is shown that the 1D solitary waves are stable to transverse perturbations.

The study of kinetic effects on Alfvén wave nonlinearity is continued. Previously obtained expressions for the perturbed (by an Alfvén wave) ion and electron distribution functions are used to obtain a nonlinear wave equation for parallel-propagating, circularly polarized waves. The results are cast in the form of a modified version of the familiar derivative nonlinear Schrödinger equation. The approach in obtaining this equation is a hybrid one; fluid theory is used to the greatest extent possible, and kinetic theory is introduced where the correction is believed to be most important. Fluid theory at two levels of sophistication is employed. The first uses a simple scalar pressure term. This approach yields physical insight and illuminates the field-aligned fluid flow and the associated plasma density perturbation as a major contributor to Alfvén wave nonlinearity. The second approach employs a tensor pressure term that in general will be necessary. The results indicate that kinetic effects in general produce a nonlinear wave equation that is of a different functional form than the derivative nonlinear Schrödinger equation, as previously reported by Mjo/lhus and Wyller [Phys. Scr. 33, 442 (1986); J. Plasma Phys. 40, 229 (1988)]. The coefficient of the derivative cubic term depends on the plasma beta in a way which, in general, is quite different from the fluid expression. In addition, a functionally novel term appears in the modified equation. The magnitude of this term, named the ‘‘nonlocal term’’ by Mjo/lhus and Wyller, can be large when the plasma beta is comparable to unity. The susceptibility of the modified equation to modulational instability is studied. Kinetic effects cause modulational instability of wave packets, even when fluid theory would predict modulational stability. This modulational instability occurs for both right- and left-hand polarized waves. This latter result might explain a property of waves near the Earth’s bow shock that was enigmatic within the context of fluid theory.

The boundness of the operator-valued functions for multidimensional nonlinear wave equations with applications

In this paper, we study a Cauchy problem for the nonlinear damped wave equations for a general positive operator with discrete spectrum. We derive the exponential in time decay of solutions to the linear problem with decay rate depending on the interplay between the bottom of the operator's spectrum and the mass term. Consequently, we prove global in time well-posedness results for semilinear and for more general nonlinear equations with small data. Examples are given for nonlinear damped wave equations for the harmonic oscillator, for the twisted Laplacian (Landau Hamiltonian), and for the Laplacians on compact manifolds.

Exact solution for (2 + 1)-dimension nonlinear dispersive long wave equation