The resolvent problem for the Stokes system in exterior domains: uniqueness and non-regularity in Hölder spaces

Author(s):  
Paul Deuring

SynopsisWe consider the resolvent problem for the Stokes system in exterior domains, under Dirichlet boundary conditions:where Ω is a bounded domain in ℝ3. It will be shown that in general there is no constant C > 0 such that for with , div u = 0, and for with . However, if a solution (u, π) of problem (*) exists, it is uniquely determined, provided that u(x) and ∇π(x) decay for large values of |x|. These assertions imply a non-existence result in Hölder spaces.

2009 ◽  
Vol 2009 ◽  
pp. 1-13 ◽  
Author(s):  
Claudio Cuevas ◽  
Carlos Lizama

We characterize well-posedness in Hölder spaces for an abstract version of the equation(∗) u′′+λu′′′=c2(Δu+μΔu′)+fwhich model thevibrationsof flexible structures possessing internal material damping and external forcef. As a consequence, we show that in case of the Laplacian with Dirichlet boundary conditions, equation(∗)is always well-posed provided0<λ<μ.


1993 ◽  
Vol 35 (1) ◽  
pp. 63-67 ◽  
Author(s):  
Patrick J. Browne ◽  
B. D. Sleeman

We are interested in two parameter eigenvalue problems of the formsubject to Dirichlet boundary conditionsThe weight function 5 and the potential q will both be assumed to lie in L2[0,1]. The problem (1.1), (1.2) generates eigencurvesin the sense that for any fixed λ, ν(λ) is the nth eigenvalue ν, (according to oscillation indexing) of (1.1), (1.2). These curves are in fact analytic functions of λ and have been the object of considerable study in recent years. The survey paper [1] provides background in this area and itemises properties of eigencurves.


2006 ◽  
Vol 2006 ◽  
pp. 1-14 ◽  
Author(s):  
Sonia Ben Othman

This paper deals with a class of singular nonlinear polyharmonic equations on the unit ballBinℝn (n≥2)where the combined effects of a singular and a sublinear term allow us by using the Schauder fixed point theorem to establish an existence result for the following problem:(−Δ)mu=φ(⋅,u)+ψ(⋅,u)inB(in the sense of distributions),u>0,lim⁡|x|→1u(x)/(1−|x|)m−1=0. Our approach is based on estimates for the polyharmonic Green function onBwith zero Dirichlet boundary conditions.


Author(s):  
Patrick Tolksdorf

Abstract The Stokes resolvent problem $$\lambda u - \Delta u + \nabla \phi = f$$ λ u - Δ u + ∇ ϕ = f with $${\text {div}}(u) = 0$$ div ( u ) = 0 subject to homogeneous Dirichlet or homogeneous Neumann-type boundary conditions is investigated. In the first part of the paper we show that for Neumann-type boundary conditions the operator norm of $$\mathrm {L}^2_{\sigma } (\Omega ) \ni f \mapsto \phi \in \mathrm {L}^2 (\Omega )$$ L σ 2 ( Ω ) ∋ f ↦ ϕ ∈ L 2 ( Ω ) decays like $$|\lambda |^{- 1 / 2}$$ | λ | - 1 / 2 which agrees exactly with the scaling of the equation. In comparison to that, the operator norm of this mapping under Dirichlet boundary conditions decays like $$|\lambda |^{- \alpha }$$ | λ | - α for $$0 \le \alpha \le 1 / 4$$ 0 ≤ α ≤ 1 / 4 and we show optimality of this rate, thereby, violating the natural scaling of the equation. In the second part of this article, we investigate the Stokes resolvent problem subject to homogeneous Neumann-type boundary conditions if the underlying domain $$\Omega $$ Ω is convex. Invoking a famous result of Grisvard (Elliptic problems in nonsmooth domains. Monographs and studies in mathematics, Pitman, 1985), we show that weak solutions u with right-hand side $$f \in \mathrm {L}^2 (\Omega ; {\mathbb {C}}^d)$$ f ∈ L 2 ( Ω ; C d ) admit $$\mathrm {H}^2$$ H 2 -regularity and further prove localized $$\mathrm {H}^2$$ H 2 -estimates for the Stokes resolvent problem. By a generalized version of Shen’s $$\mathrm {L}^p$$ L p -extrapolation theorem (Shen in Ann Inst Fourier (Grenoble) 55(1):173–197, 2005) we establish optimal resolvent estimates and gradient estimates in $$\mathrm {L}^p (\Omega ; {\mathbb {C}}^d)$$ L p ( Ω ; C d ) for $$2d / (d + 2)< p < 2d / (d - 2)$$ 2 d / ( d + 2 ) < p < 2 d / ( d - 2 ) (with $$1< p < \infty $$ 1 < p < ∞ if $$d = 2$$ d = 2 ). This interval is larger than the known interval for resolvent estimates subject to Dirichlet boundary conditions (Shen in Arch Ration Mech Anal 205(2):395–424, 2012) on general Lipschitz domains.


Author(s):  
M. Chhetri ◽  
S. Raynor ◽  
S. Robinson

We use the method of upper and lower solutions combined with degree-theoretic techniques to prove the existence of multiple positive solutions to some superlinear elliptic systems of the formon a smooth, bounded domain Ω⊂ℝn with Dirichlet boundary conditions, under suitable conditions on g1 and g2. Our techniques apply generally to subcritical, superlinear problems with a certain concave–convex shape to their nonlinearity.


2019 ◽  
Vol 150 (4) ◽  
pp. 2025-2054
Author(s):  
Piotr Kalita ◽  
Piotr Zgliczyński

AbstractWe study the non-autonomously forced Burgers equation $$u_t(x,t) + u(x,t)u_x(x,t)-u_{xx}(x,t) = f(x,t)$$ on the space interval (0, 1) with two sets of the boundary conditions: the Dirichlet and periodic ones. For both situations we prove that there exists the unique H1 bounded trajectory of this equation defined for all t ∈ ℝ. Moreover we demonstrate that this trajectory attracts all trajectories both in pullback and forward sense. We also prove that for the Dirichlet case this attraction is exponential.


2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Eva Llabrés

Abstract We find the most general solution to Chern-Simons AdS3 gravity in Fefferman-Graham gauge. The connections are equivalent to geometries that have a non-trivial curved boundary, characterized by a 2-dimensional vielbein and a spin connection. We define a variational principle for Dirichlet boundary conditions and find the boundary stress tensor in the Chern-Simons formalism. Using this variational principle as the departure point, we show how to treat other choices of boundary conditions in this formalism, such as, including the mixed boundary conditions corresponding to a $$ T\overline{T} $$ T T ¯ -deformation.


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