arXiv subjects

Jung-Tae Park

Publications and source records attributed to Jung-Tae Park.

7 recordsLinked to original sources

arXiv2026

Existence of weak solutions for nonlinear drift-diffusion equations with measure data

We consider nonlinear drift-diffusion equations (both porous medium equations and fast diffusion equations) with measure data. We establish the existence of nonnegative weak solutions satisfying gradient estimates, provided that the drift term belongs to a sub-scaling class relevant to the $L^1$ space. When the drift is divergence-free, this requirement can be relaxed: the drift may belong to a class that is supercritical with respect to $L^1$-scaling class, and the admissible range of the diffusion exponent $m$ is enlarged as well. By handling both the measure data and the drift, we obtain a new type of energy estimate. We also discuss sharpness by constructing counterexamples showing that the general-drift range cannot be improved under the corresponding integrability scale without the divergence-free cancellation. As an application, we construct weak solutions for a specific type of nonlinear diffusion equation with measure data coupled to the incompressible Navier-Stokes equations.

math.AP↗

arXiv2022

Regularity estimates for singular parabolic measure data problems with sharp growth

We prove global gradient estimates for parabolic $p$-Laplace type equations with measure data, whose model is $$u_t - \textrm{div} \left(|Du|^{p-2} Du\right) = μ\quad \textrm{in} \ Ω\times (0,T) \subset \mathbb{R}^n \times \mathbb{R},$$ where $μ$ is a signed Radon measure with finite total mass. We consider the singular case $$\frac{2n}{n+1} <p \le 2-\frac{1}{n+1}$$ and give possibly minimal conditions on the nonlinearity and the boundary of $Ω$, which guarantee the regularity results for such measure data problems.

math.AP↗

arXiv2022

Marcinkiewicz regularity for singular parabolic $p$-Laplace type equations with measure data

We consider quasilinear parabolic equations with measurable coefficients when the right-hand side is a signed Radon measure with finite total mass, having $p$-Laplace type: $$u_t - \textrm{div} \, \mathbf{a}(Du,x,t) = μ\quad \textrm{in} \ Ω\times (0,T) \subset \mathbb{R}^n \times \mathbb{R}.$$ In the singular range $\frac{2n}{n+1} <p \le 2-\frac{1}{n+1}$, we establish regularity estimates for the spatial gradient of solutions in the Marcinkiewicz spaces, under a suitable density condition of the right-hand side measure.

math.AP↗

arXiv2021

Nonlinear gradient estimates for elliptic double obstacle problems with measure data

We study quasilinear elliptic double obstacle problems with a variable exponent growth when the right-hand side is a measure. A global Calderón-Zygmund estimate for the gradient of an approximable solution is obtained in terms of the associated double obstacles and a given measure, identifying minimal requirements for the regularity estimate.

math.AP↗

arXiv2021

Global regularity for degenerate/singular parabolic equations involving measure data

We consider degenerate and singular parabolic equations with $p$-Laplacian structure in bounded nonsmooth domains when the right-hand side is a signed Radon measure with finite total mass. We develop a new tool that allows global regularity estimates for the spatial gradient of solutions to such parabolic measure data problems, by introducing the (intrinsic) fractional maximal function of a given measure.

math.AP↗

arXiv2018

End point gradient estimates for quasilinear parabolic equations with variable exponent growth on nonsmooth domains

In this paper, we study quasilinear parabolic equations with the nonlinearity structure modeled after the $p(x,t)$-Laplacian on nonsmooth domains. The main goal is to obtain end point Calderón-Zygmund type estimates in the variable exponent setting. In a recent work \cite{byun2016nonlinear}, the estimates obtained were strictly above the natural exponent $p(x,t)$ and hence there was a gap between the natural energy estimates and the estimates above $p(x,t)$ (see \eqref{energy} and \eqref{byunok}). Here, we bridge this gap to obtain the end point case of the estimates obtained in \cite{byun2016nonlinear}. To this end, we make use of the parabolic Lipschitz truncation developed in \cite{KL} and obtain significantly improved a priori estimates below the natural exponent with stability of the constants. An important feature of the techniques used here is that we make use of the unified intrinsic scaling introduced in \cite{adimurthi2018sharp}, which enables us to handle both the singular and degenerate cases simultaneously.

math.AP↗

arXiv2017

Sharp gradient estimates for quasilinear elliptic equations with $p(x)$ growth on nonsmooth domains

In this paper, we study quasilinear elliptic equations with the nonlinearity modelled after the $p(x)$-Laplacian on nonsmooth domains and obtain sharp Calderón-Zygmund type estimates in the variable exponent setting. In a recent work of \cite{BO}, the estimates obtained were strictly above the natural exponent and hence there was a gap between the natural energy estimates and estimates above $p(x)$, see \eqref{energy_introduction} and \eqref{byun_ok_estimate}. Here, we bridge this gap to obtain the end point case of the estimates obtained in \cite{BO}, see \eqref{our_estimate}. In order to do this, we have to obtain significantly improved a priori estimates below $p(x)$, which is the main contribution of this paper. We also improve upon the previous results by obtaining the estimates for a larger class of domains than what was considered in the literature.

math.AP↗