arXiv subjects

Lucas C. F. Ferreira

Publications and source records attributed to Lucas C. F. Ferreira.

At least 19 recordsLinked to original sources

arXiv2026

On product estimates in Besov-Morrey spaces and stationary solutions for the Hall-MHD and Navier-Stokes systems

In this paper, we investigate the well-posedness of the three-dimensional stationary incompressible resistive-viscous Hall magnetohydrodynamic (Hall-MHD) system within the framework of scale-invariant Besov-Morrey spaces. A key component of our analysis is the derivation of product estimates in these spaces, which are instrumental in handling the system's nonlinear terms. As an application, we also establish a well-posedness result for the stationary Navier-Stokes equations in this setting, thereby broadening the admissible classes of external forces and solutions.

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arXiv2026

Well-posedness for the Navier-Stokes equations in Morrey spaces on non-compact manifolds

We analyze the incompressible Navier-Stokes equations on a class of non-compact Riemannian manifolds within the framework of Morrey spaces. Assuming bounded geometry together with negative Ricci and sectional curvature (e.g., hyperbolic spaces), we establish dispersive and smoothing estimates for the heat semigroups associated with the Beltrami, Bochner and Hodge Laplacians in Morrey spaces, as well as for the Riesz transform. In particular, the presence of negative curvature yields improved large-time decay compared to the Euclidean setting. These estimates are of independent interest and enable us to construct solutions in time-weighted spaces of Kato type, leading to local-in-time well-posedness on a broad class of non-compact manifolds and global one in the case of Einstein manifolds. In the latter setting, we assume a smallness condition on the initial data in Morrey norms, which are weaker than $L^{p}$-norms and thus allow for certain classes of large $L^{p}$-data. We also discuss extensions to Ricci-flat manifolds. Our results introduce a new class of non-decaying and rough initial data for the Navier-Stokes equations on manifolds, extending previous works in Lebesgue and Sobolev spaces.

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arXiv2026

On the global well-posedness and self-similar solutions for a nonlinear elliptic problem with a dynamic boundary condition

We are concerned with a semilinear elliptic equation in the half-space, subject to a nonlinear dynamic boundary condition. We establish the global well-posedness of solutions in a new setting for the problem, namely the framework of Morrey spaces. These are strictly larger than $L^{p}$ and weak-$L^{p}$ spaces, accommodating a broader class of rough initial data, including homogeneous and nondecaying (at infinity) profiles. In our analysis, we consider functional spaces invariant under the natural scaling of the problem, which enables the construction of self-similar solutions. To achieve this, we need to derive key estimates in Morrey spaces for certain interior and boundary operators that arise from the corresponding integral formulation. Furthermore, we obtain some qualitative properties of the solutions, such as positivity, symmetry, and asymptotic stability. Leveraging this last property, we show the existence of self-similar attractor basins and construct a class of solutions that are asymptotically self-similar.

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arXiv2025

Existence of hyperbolic blow-up to the generalized quasi-geostrophic equation

In this work, we investigate the blow-up of solutions to the generalized surface quasi-geostrophic (gSQG) equation in $\mathbb{R}^{2}$, within the more singular range $β\in(1,2)$ for the coupling of the velocity field. This behavior is studied under a hyperbolic setting based on the framework originally introduced by Córdoba (1998, Annals of Math. 148, 1135--52) for the classical SQG equation. Assuming that the level sets of the solution contains a hyperbolic saddle, and under suitable conditions on the solution at the origin, we obtain the existence of a time $T^{\ast}\in\mathbb{R}^{+}\cup\{\infty\}$ at which the opening angle of the saddle collapses. Moreover, we derive a lower bound for the blow-up time $T^\ast$. This geometric degeneration leads to the blow-up of the Hölder norm $\Vertθ(t)\Vert_{C^σ}$ as $t\rightarrow T^{\ast}$, for $σ\in(0, β-1)$, showing the formation of singularity in the Hölder space at time $T^{\ast}$. To the best of our knowledge, these are the first results in the literature to rigorously prove the formation of a singularity, whether in finite or infinite time, for a class of smooth solutions to the gSQG equation.

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arXiv2025

Existence of nested polygonal vortex patches for the generalized SQG equation

This paper investigates time-periodic solutions of both the surface quasi-geostrophic (SQG) equation and its generalized form (gSQG) within the more singular regime, focusing on the evolution of patch-type structures. Assuming the underlying point vortex equilibrium satisfies a natural nondegeneracy condition, we employ an implicit function argument to construct families of co-rotating nested polygonal vortex patch solutions. These configurations provide precise asymptotic descriptions of the geometry of the evolving patch boundaries. Our results contribute to the broader understanding of coherent rotating structures arising in active scalar equations with singular velocity coupling.

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arXiv2024

On the Helmholtz decomposition in Morrey and block spaces

In this work, we obtain the Helmholtz decomposition for vector fields in Morrey, Zorko, and block spaces over bounded or exterior $C^{1}$ domains. Generally speaking, our proofs rely on a careful interplay of localization, flattening, and duality arguments. To accomplish this, we need to extend some classical tools in analysis and PDE theory to those spaces, including Stein extensions, compact embeddings, Poincaré inequalities, Bogovskii-type theorem, among other ingredients. Some of these findings may be of independent interest and applied to the study of a number of PDEs.

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arXiv2024

On the well-posedness of the Hall-MHD system in a critical setting of Besov-Morrey type

In this paper, we address the 3D incompressible Hall-magnetohydrodynamic system (Hall-MHD). Our objective is to provide local and global well-posedness results for initial velocity $u_{0}$, magnetic field $B_{0}$ and the current $J_{0}:=\nabla\times B_{0}$ in a new critical framework, namely critical Besov-Morrey spaces. These spaces combine typical characteristics from both Besov and Morrey spaces allowing a broader framework that encompasses the regularity properties inherent in Besov spaces with the Morrey space structure. Compared to previous works in Sobolev and Besov spaces, our approach accommodates a broader class of initial data, ensuring the construction of a unique solution over time.

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arXiv2024

Dispersive estimates and generalized Boussinesq equation on hyperbolic spaces with rough initial data

We consider the generalized Boussinesq (GBq) equation on the real hyperbolic space $\mathbb{H}^{n}$ ($n\geq2$) in a rough framework based on Lorentz spaces. First, we establish dispersive estimates for the GBq-prototype group, which is associated with a core term of the linear part of the GBq equation, through a manifold-intrinsic Fourier analysis and estimates for oscillatory integrals in $\mathbb{H}^{n}$. Then, we obtain dispersive estimates for the GBq-prototype and Boussinesq groups on Lorentz spaces in the context of $\mathbb{H}^{n}$. Employing those estimates, we obtain local and global well-posedness results and scattering properties in such framework. Moreover, we prove the polynomial stability of mild solutions and leverage this to improve the scattering decay.

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arXiv2024

Global solutions for a 2D chemotaxis-fluid system with large measures as initial density and vorticity

We consider a chemotaxis-fluid system in the whole plane $\mathbb{R}^{2}$ which describes the motion of bacteria suspended in a Navier-Stokes fluid and attracted by a chemical (oxygen). Employing the vorticity formulation for the fluid equations, we obtain local and global solutions with large (Radon) measures as initial data for the bacterial density and vorticity. The gravitational/centrifugal potential is taken with finite $L^{2}$-gradient that can be large. The uniqueness property is also discussed. For the global result, we need to assume a smallness condition only on the $L^{\infty}$-norm of the initial oxygen concentration. In comparison with previous works, our results provide a new class for the initial density and vorticity, as well as for the potential, covering particularly singular measures such as Dirac delta, measure concentrated on smooth curves (filaments and rings), among others. For that, we approach the system via critical functional spaces, Kato-type norms, and suitable $L^{p}$-estimates uniformly in time.

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arXiv2024

Well-posedness and scattering for wave equations on hyperbolic spaces with singular data

We consider the wave and Klein-Gordon equations on the real hyperbolic space $\mathbb{H}^{n}$ ($n \geq2$) in a framework based on weak-$L^{p}$ spaces. First, we establish dispersive estimates on Lorentz spaces in the context of $\mathbb{H}^{n}$. Then, employing those estimates, we prove global well-posedness of solutions and an exponential asymptotic stability property. Moreover, we develop a scattering theory and construct wave operators in such singular framework.

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arXiv2024

Existence of stationary vortex patches for the gSQG in bounded domains

In this paper we show the existence of time-periodic vortex patches for the generalized surface quasi-geostrophic equation within a bounded domain. This construction is carried out for values of $γ$ in the range of $(1,2)$. The resulting vortex patches possess a fixed vorticity and total flux, and they are located in the neighborhood of critical points that are non-degenerate for the Kirchhoff--Routh equation. The proof is accomplished through a combination of analyzing the linearization of the contour dynamics equation and employing the implicit function theorem as well as carefully selected function spaces.

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arXiv2024

On bilinear estimates and critical uniqueness classes for Navier-Stokes equations

We are concerned with bilinear estimates and uniqueness of mild solutions for the Navier-Stokes equations in critical spaces. For that, we construct general settings in which estimates for the bilinear term of the mild formulation hold true without using auxiliary norms such as Kato time-weighted ones. We first obtain necessary conditions in abstract critical spaces and then consider further structures to obtain the estimates in general classes of Besov, Morrey and Besov-Morrey spaces based on Banach spaces. Examples of applications are provided in different spaces as well as for other PDEs. In particular, as far as we know, the bilinear estimate and the uniqueness property obtained in the framework of Besov-weak-Herz spaces are not available in the existing literature. The proofs are mainly based on characterizations and estimates on the corresponding predual spaces.

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arXiv2023

Long-time solvability for the 2D inviscid Boussinesq equations with borderline regularity and dispersive effects

We are concerned with the long-time solvability for 2D inviscid Boussinesq equations for a larger class of initial data which covers the case of borderline regularity. First we show the local solvability in Besov spaces uniformly with respect to a parameter $κ$ associated with the stratification of the fluid. Afterwards, employing a blow-up criterion and Strichartz-type estimates, the long-time solvability is obtained for large $κ$ regardless of the size of initial data.

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arXiv2023

Existence of vortex sheet solutions to the SQG Equation

This paper addresses the existence of vortex sheets for the SQG equation. More precisely, we construct a family of stationary vortex sheet solutions that are concentrated on curves that are small perturbations of circles centered on a given non-degenerate critical point. To the best of our knowledge, this is a novel result on the existence of vortex sheets to the SQG equation.

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arXiv2023

Local and global analysis in Besov-Morrey spaces for inhomogeneous Navier-Stokes equations

In this paper we consider the incompressible inhomogeneous Navier-Stokes equations in the whole space with dimension $n\geq 3$. We present local and global well-posedness results in a new framework for inhomogeneous fluids, namely Besov-Morrey spaces $\mathcal{N}_{p,q,r}^{s}$ that are Besov spaces based on Morrey ones. In comparison with the previous works in Sobolev and Besov spaces, our results provide a larger initial-data class for both the velocity and density, constructing a unique global-in-time flow under smallness conditions on weaker initial-data norms. In particular, we can consider some kind of initial discontinuous densities, since our density class $\mathcal{N}_{p,q,\infty }^{n/p}\cap L^{\infty }$ is not contained in any space of continuous functions. From a technical viewpoint, the Morrey underlying norms prevent the common use of energy-type and integration by parts arguments, and then we need to obtain some estimates for the localizations of the heat semigroup, the commutator, and the volume-preserving map in our setting, as well as estimates for transport equations and the linearized inhomogeneous Navier-Stokes system.

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arXiv2023

On the well-posedness in Besov-Herz spaces for the inhomogeneous incompressible Euler equations

In this paper we study the inhomogeneous incompressible Euler equations in the whole space $\mathbb{R}^n$ with $n\geq3$. We obtain well-posedness and blow-up results in a new framework for inhomogeneous fluids, more precisely Besov-Herz spaces that are Besov spaces based on Herz ones, covering particularly critical cases of the regularity. Comparing with previous works on Besov spaces, our results provide a larger initial data class for a well-defined flow. For that, we need to obtain suitable linear estimates for some conservation-law models in our setting such as transport equations and the linearized inhomogeneous Euler system.

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arXiv2022

Existence of asymmetric vortex patch for the generalized SQG equations

This paper aims to study the existence of asymmetric solutions for the two-dimensional generalized surface quasi-geostrophic (gSQG) equations of simply connected patches for $α\in[1,2)$ in the whole plane, where $α=1$ corresponds to the surface quasi-geostrophic equations (SQG). More precisely, we construct non-trivial simply connected co-rotating and traveling patches with unequal vorticity magnitudes. The proof is carried out by means of a combination of a desingularization argument with the implicit function theorem on the linearization of contour dynamics equation. Our results extend recent ones in the range $α\in[0,1)$ by Hassainia-Hmidi (DCDS-A, 2021) and Hassainia-Wheeler (SIAM J. Math. Anal., 2022) to more singular velocities, filling an open gap in the range of $α$.

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arXiv2020

Global well-posedness for the fractional Boussinesq-Coriolis system with stratification in a framework of Fourier-Besov type

We establish the global well-posedness of the 3D fractional Boussinesq-Coriolis system with stratification in a framework of Fourier type, namely spaces of Fourier-Besov type with underlying space being Morrey spaces (FBM-spaces, for short). Under suitable conditions and rescaled density fluctuation, the result is uniform with respect to the Coriolis and stratification parameters. We cover the critical case of the dissipation, namely half-Laplacian, in which the nonlocal dissipation has the same differential order as the nonlinearity and balances critically the scaling of the quadratic nonlinearities. As a byproduct, considering trivial initial temperature and null stratification, we also obtain well-posed results in FBM-spaces for the fractional Navier-Stokes-Coriolis system as well as for the Navier-Stokes equations with critical dissipation. Moreover, since small conditions are taken in the weak norm of FBM-spaces, we can consider some initial data with arbitrarily large $H^{s}$-norms, $s\geq0$.

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