Global Lp-properties for the spatially homogeneous Boltzmann equation

This paper studies the L ^p-behavior for 1p of solutions of the nonlinear, spatially homogeneous Boltzmann equation for a class of collision kernels including inverse k ^th-power forces with k>5 and angular cut-off. The following topics are treated: differentiability in L ^p together with global boundedness in time for L ^p-moments that exist initially, translation continuity in L ^p uniformly in time, and strong convergence to equilibrium.     

Lp-estimates for the nonlinear spatially homogeneous Boltzmann equation

This paper studies L^p-estimates for solutions of the nonlinear, spatially homogeneous Boltzmann equation. The molecular forces considered include inverse k^th-power forces with k > 5 and angular cut-off.The main conclusions are the following. Let f be the unique solution of the Boltzmann equation with f(v,t)(1 + ¦v²¦)^(s ₁ ^{+ /p)/2} L¹, when the initial value f ₀ satisfies f ₀(v) 0, f ₀(v) (1 + ¦v¦²)^(s ₁ ^{+ /p)/2} L¹, for some s₁ 2 + /p, and f ₀(v) (1 + ¦v¦²)^s/2 L^p. If s 2/p and 1 < p < , then f(v, t)(1 + ¦v¦²)^{(s s} ₁)^/2 L^p, t > 0. If s >2 and 3/(1+ ) < p < , thenf(v,t) (1 + ¦v¦²)^(s(s ₁ ^{+ 3/p))/2} L^p, t > 0. If s >2 + 2C₀/C₁ and 3/(l + ) < p < , then f(v,t)(1 + ¦v¦²)^s/2 L^p, t > 0. Here 1/p + 1/p = 1, x y = min (x, y), and C₀, C₁, 0 < 1, are positive constants related to the molecular forces under consideration; = (k – 5)/ (k – 1) for k^th-power forces.Some weaker conclusions follow when 1 < p 3/ (1 + ).In the proofs some previously known L-estimates are extended. The results for L^p, 1 < p < , are based on these L-estimates coupled with nonlinear interpolation.     

New a priori estimates for the spatially homogeneous Boltzmann equation

Given the solutionf(t) to the spatially homogeneous Boltzmann equation, we study the time evolution of the Linnik's functionalJ(f(t)).When the Boltzmann equation for Maxwellian pseudomolecules with planar velocities is considered, it is proven thatJ(f(t)) is decreasing in time.     

Stability and exponential convergence for the Boltzmann equation

We prove existence, uniqueness and stability for solutions of the nonlinear Boltzmann equation in a periodic box in the case when the initial data are sufficiently close to a spatially homogeneous function. The results are given for a range of spaces, including L ¹, and extend previous results in L for the non-homogeneous equation, as well as the more developed L ^p -theory for the spatially homogeneous Boltzmann equation.We also give new L -estimates for the spatially homogeneous equation in the case of Maxwellian interactions.     

Solution of a nonlinear Boltzmann equation for neutron transport in L1 space

The aim of this paper is to give a constructive method for the solution of the Boltzmann equation for neutron transport in a bounded space domain subject to typical boundary and initial conditions. Sufficient conditions are given to insure the existence of a unique solution. The method entails the use of a semiinner product in a Banach space together with successive approximations, and leads to a recursion formula for the calculation of approximate solutions and error estimates. The linearized Boltzmann equation for neutron transport is included as a special case.     

L 1 and BV-type stability of the inelastic Boltzmann equation near vacuum

The L ¹ and BV-type stability to mild solutions of the inelastic Boltzmann equation is given in this paper. The result is an extension of the stability of the classical solution of the elastic Boltzmann equation proved in Ha (Arch. Ration. Mech. Anal. 173:25–42, 2004 [16]). The observation relies on the energy loss of the inelastic Boltzmann equation. This is a continuity work of Alonso (Indiana Univ. Math. J. [1]), where the author obtained the global existence of a mild solution for the inelastic Boltzmann equation. The proof is based on the mollification method and constructing some functionals as the one in Chae and Ha (Contin. Mech. Thermodyn. 17(7):511–524, 2006 [9]).     

Stability estimates of the Boltzmann equation with quantum effects

We study uniform stability estimates to the Boltzmann equation for quantum particles such as Bose-Einstein particles and Fermi-Dirac particles. When the small amount of particles expands toward the vacuum, we show that continuous mild solutions are L ¹-stable and also satisfy BV-type estimates using a nonlinear functional approach. PACS05.20 Dd     

On group classification of the spatially homogeneous and isotropic Boltzmann equation with sources

In Nonenmacher (1984) [1] an admitted Lie group of transformations for the spatially homogeneous and isotropic Boltzmann equation with sources was studied. In fact, the author is Nonenmacher (1984) [1] considered the equation for a generating function of the power moments of the Boltzmann equation solution. However, this equation is still a non-local partial differential equation, and this property was not taken into account there. In the present paper the admitted Lie group of this equation is studied, using our original method developed for group analysis of equations with non-local operators (Grigoriev and Meleshko, 1986; Meleshko, 2005; Grigoriev et al., 2010 [2], [3], [4]). The Lie groups obtained are compared with Nonenmacher (1984) [1]. The deficiency of Nonenmacher (1984) [1] is corrected.     

On group classification of the spatially homogeneous and isotropic Boltzmann equation with sources II

A previous paper by the authors (Grigoriev and Meleshko, 2012 [4]) was devoted to group analysis of the equation for the power moment generating function of a solution of the Boltzmann kinetic equation with sources. An approach developed earlier by Grigoriev and Meleshko (1986 [2]) was employed for finding the admitted Lie group. This approach allowed to correct Nonenmacher׳s results (1984, [1]) and to perform a partial group classification of the considered equation with respect to a source function. The present paper completes this group classification by an efficient algebraic method.     

The semidiscrete Boltzmann equation for hard-spheres

Summary This paper deals with a semi-discrete model of the Boltzmann equation, such that the velocity distribution is discretized in modulus, but non in direction. The mathematical model is described in details, then the formulation of the initial value problem is proposed; the mathematical analysis supplies some rigorous results on the global mild solution and on its asymptotic behaviour.

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Sommario Si studia un modello di equazione di Boltzmann semidiscreta, caratterizzato dal fatto che le velocità sono discretizzate in modulo e non in direzione. Viene descritto in dettaglio il modello, quindi si studia il problema di Cauchy, fornendo indicazioni sul comportamento asintotico della soluzione.

     

The cumulant method for the space-homogeneous Boltzmann equation

In this work we give a comparison of the exact Bobylev/Krook-Wu solution to the space-homogeneous Boltzmann equation and numerical results obtained by a implementation of the cumulant method for the space-homogeneous case. We find excellent agreement of the numerical solution to the cumulant equations with the exact solution of the space-homogeneous Boltzmann equation as long as the exact, non-linear production terms are used. If a linearized variant of the production terms is used, relaxation rates may be underestimated due to convergence to the solution of the linearized equations.Received: 3 April 2004, Accepted: 3 September 2004, Published online: 22 February 2005PACS: 51.10. + y, 51.30. + i, 47.11 + j, 47.45.-n Correspondence to: K.H. Hoffmann     

On the initial-boundary value problem for the Boltzmann equation

A theorem on the traces of the solutions of initial-boundary value problems for the Boltzmann equation is proved. This result makes it possible to extend a recent theorem of existence proved by Hamdache to more realistic situations.     

Exact solution of the Boltzmann equation

We build up immediate connection between the nonlinear Boltzmann transport equation and the linear AKNS equation, and classify the Boltzmann equation as the Dirac equation by a new method for solving the Boltzmann equation out of keeping with the Chapman, Enskog and Grad’s way in this paper. Without the effect of other external fields, the exact solution of the Boltzmann equation can be obtained by the inverse scattering method.     

Existence of homoenergetic affine flows for the Boltzmann equation

An existence theorem is proved for homoenergetic affine flows described by the Boltzmann equation. The result complements the analysis of Truesdell and of Galkin on the moment equations for a gas of Maxwellian molecules. Existence of the distribution function is established here for a large class of molecular models (hard sphere and angular cut-off interactions). Some of the data lead to an implosion and infinite density in a finite time, in agreement with the physical picture of the associated flows; for the remaining set of data, global existence is shown to hold.     

A lattice Boltzmann method for KDV equation

We prepose a 5-bit lattice Boltzmann model for KdV equation. Using Chapman-Enskog expansion and multiscale technique, we obtained high order moments of equilibrium distribution function, and the 3rd dispersion coefficient and 4th order viscosity. The parameters of this scheme can be determined by analysing the energy dissipation. The project supported by the Foundation of the Laboratory for Nonlinear Mechanics of Continuous Media, Institute of Mechanics, Chinese Academy of Sciences     

Boltzmann equation in the α, u representation

It is proposed, as in [1, 2], to regard the distribution function as a set of all possible Maxwellian distributions with arbitrary temperatures and mean velocities, with each Maxwelian distribution taken with its own weight (, u). An equation equivalent to the Boltzmann equation is constructed for this weight function. The cases of one-dimensional, twodimensional, operator in the arbitrary case in the , u representation it suffices to know the corresponding kernel for the one-dimensional problem.Leningrad. Traslated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 117–123, July–August, 1972.     

Conditions of applicability of the Boltzmann equation

The existence of certain characteristic times, introduced by Bogolyubov [1], is of fundamental importance for the derivation of the Boltzmann equation from the Liouville equations. In the present paper characteristic spatial scales are also introduced, which permit a more detailed study of the influence of spatial gradients and boundary conditions. A convenient formalism, which is a generalization of the formalism of [2], is used in this study. The following has been shown for a Boltzmann gas (compare [1–4]):

1. a)
   The Boltzmann equation is applicable for describing flows in which the condition of molecular chaos is satisfied and in which the characteristic dimension L (time T) is much greater than the diameter d (time τ_c) of molecular interactions.