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Nonlocal quadratic evolution problems

Piotr Biler, Wojbor Woyczyński (2000)

Banach Center Publications

Nonlinear nonlocal parabolic equations modeling the evolution of density of mutually interacting particles are considered. The inertial type nonlinearity is quadratic and nonlocal while the diffusive term, also nonlocal, is anomalous and fractal, i.e., represented by a fractional power of the Laplacian. Conditions for global in time existence versus finite time blow-up are studied. Self-similar solutions are constructed for certain homogeneous initial data. Monte Carlo approximation schemes by interacting...

Non-negative solutions of generalized porous medium equations.

Bjorn E. J. Dahlberg, Carlos E. Kenig (1986)

Revista Matemática Iberoamericana

The purpose of this paper is to study nonnegative solutions u of the nonlinear evolution equations∂u/∂t = Δφ(u),  x ∈ Rn, 0 < t < T ≤ +∞  (1.1)Here the nonlinearity φ is assumed to be continuous, increasing with φ(0) = 0. This equation arises in various physical problems, and specializing φ leads to models for nonlinear filtrations, or for the gas flow in a porous medium. For a recent survey in these equations see [9].The main object of this work is to study the initial value problem...

Non-negative solutions to fast diffusions.

Bjorn E. J. Dahlberg, Carlos E. Kenig (1988)

Revista Matemática Iberoamericana

The purpose of this work is to study the class of non-negative continuous weak solutions of the non-linear evolution equation∂u/∂t = ∆φ(u),   x ∈ Rn, 0 < t < T ≤ +∞.

Nonuniqueness of implicit lattice Nagumo equation

Petr Stehlík, Jonáš Volek (2019)

Applications of Mathematics

We consider the implicit discretization of Nagumo equation on finite lattices and show that its variational formulation corresponds in various parameter settings to convex, mountain-pass or saddle-point geometries. Consequently, we are able to derive conditions under which the implicit discretization yields multiple solutions. Interestingly, for certain parameters we show nonuniqueness for arbitrarily small discretization steps. Finally, we provide a simple example showing that the nonuniqueness...

Nonvariational basic parabolic systems of second order

Sergio Campanato (1991)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Ω is a bounded open set of R n , of class C 2 and T > 0 . In the cylinder Q = Ω × 0 , T we consider non variational basic operator a H u - u / t where a ξ is a vector in R N , N 1 , which is continuous in ξ and satisfies the condition (A). It is shown that f L 2 Q the Cauchy-Dirichlet problem u W 0 2 , 1 Q , a H u - u / t = f in Q , has a unique solution. It is further shown that if u W 0 2 , 1 Q is a solution of the basic system a H u - u / t = 0 in Q , then H u and u / t belong to H l o c 1 Q . From this the Hölder continuity in Q of the vectors u and D u are deduced respectively when n 4 and n = 2 .

Note on blow-up of solutions for a porous medium equation with convection and boundary flux

Zhiyong Wang, Jingxue Yin (2012)

Colloquium Mathematicae

De Pablo et al. [Proc. Roy. Soc. Edinburgh Sect. A 138 (2008), 513-530] considered a nonlinear boundary value problem for a porous medium equation with a convection term, and they classified exponents of nonlinearities which lead either to the global-in-time existence of solutions or to a blow-up of solutions. In their analysis they left open the case of a certain critical range of exponents. The purpose of this note is to fill this gap.

Note on the internal stabilization of stochastic parabolic equations with linearly multiplicative gaussian noise

Viorel Barbu (2013)

ESAIM: Control, Optimisation and Calculus of Variations

The parabolic equations driven by linearly multiplicative Gaussian noise are stabilizable in probability by linear feedback controllers with support in a suitably chosen open subset of the domain. This procedure extends to Navier − Stokes equations with multiplicative noise. The exact controllability is also discussed.

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