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Jae-Myoung Kim

Publications and source records attributed to Jae-Myoung Kim.

11 recordsLinked to original sources
arXiv2026

Stability and instability for the fully parabolic Keller-Segel system around constant equilibrium

This paper studies the Cauchy problem for the fully parabolic Keller-Segel system. The main results show that there exists a critical threshold $A_{\rm crit}>0$ for steady states $(A,A)$ such that the steady states are nonlinearly stable when $A\le A_{\rm crit}$ and nonlinearly unstable when $A>A_{\rm crit}$. We discuss asymptotic convergence rates as well. In the subcritical case $A<A_{\rm crit}$, the rates correspond to those of the heat equation, and in the critical case $A=A_{\rm crit}$, the rates correspond to half those of the heat equation.

math.AP↗
arXiv2023

Some Liouville-type theorems for the stationary 3D magneto-micropolar fluids

In this paper we prove some Liouville-type theorems for the stationary magneto-micropolar fluids under suitable conditions in three space dimensions. We first prove that the solutions are trivial under the assumption of certain growth conditions for the mean oscillations of the potentials. And then we show similar results assuming that the the solutions are contained in $L^p(\mathbb{R}^3)$ with $p\in[2,9/2)$. Finally we show the same result for lower values of $p\in[1,9/4)$ with the further assumption that the solutions vanish at infinity.

math.AP↗
arXiv2022

Liouville type Theorems for the stationary compressible 3D MHD equations

In this paper, we investigate the three dimensional stationary compressible Navier-Stokes equations, and obtain Liouville type theorems if a smooth solution $(ρ, \mathbf{u})$ satisfies some suitable conditions. In particular, our results improve and generalize the corresponding result.

math.AP↗
arXiv2022

Upper and lower bounds of convergence rates for strong solutions of the generalized Newtonian fluids with non-standard growth conditions

We consider the motion of an incompressible shear-thickening power-law-like non-Newtonian fluid in $R^3$ with a variable power-law index. This system of nonlinear partial differential equations arises in mathematical models of electrorheological fluids. The aim of this paper is to investigate the large-time behaviour of the difference $u-\tilde{u}$ where $u$ is a strong solution of the given equations with the initial data $u_0$ and $\tilde{u}$ is the strong solution of the same equations with perturbed initial data $u_0+w_0$. The initial perturbation $w_0$ is not required to be small, but is assumed to satisfy certain decay condition. In particular, we can show that $(1+t)^{-\fracγ{2}}\lesssim \|u(t)-\tilde{u}(t)\|_2\lesssim(1+t)^{-\fracγ{2}}$, for sufficiently large $t>0$, where $γ\in(2,\frac{5}{2})$. The proof is based on the observation that the solution of the linear heat equation describes the asymptotic behaviour of the solutions of the electrorheological fluids well for sufficiently large time $t>0$, and the generalized Fourier splitting method with an iterative argument. Furthermore, it will also be discussed that the argument used in the present paper can improve the previous results for the generalized Newtonian fluids with a constant power-law index.

math.AP↗
arXiv2020

Temporal decays and asymptotic behaviors for a Vlasov equation with a flocking term coupled to incompressible fluid flow

We are concerned with large-time behaviors of solutions for Vlasov--Navier--Stokes equations in two dimensions and Vlasov-Stokes system in three dimensions including the effect of velocity alignment/misalignment. We first revisit the large-time behavior estimate for our main system and refine assumptions on the dimensions and a communication weight function. In particular, this allows us to take into account the effect of the misalignment interactions between particles. We then use a sharp heat kernel estimate to obtain the exponential time decay of fluid velocity to its average in $L^\infty$-norm. For the kinetic part, by employing a certain type of Sobolev norm weighted by modulations of averaged particle velocity, we prove the exponential time decay of the particle distribution, provided that local particle distribution function is uniformly bounded. Moreover, we show that the support of particle distribution function in velocity shrinks to a point, which is the mean of averaged initial particle and fluid velocities, exponentially fast as time goes to infinity. This also provides that for any $p \in [1,\infty]$, the $p$-Wasserstein distance between the particle distribution function and the tensor product of the local particle distributions and Dirac measure at that point in velocity converges exponentially fast to zero as time goes to infinity.

math.AP↗
arXiv2018

Existence of regular solutions for a certain type of non-Newtonian Navier-Stokes equations

We are concerned with existence of regular solutions for non-Newtonian fluids in dimension three. For a certain type of non-Newtonian fluids we prove local existence of unique regular solutions, provided that the initial data are sufficiently smooth. Moreover, if the $H^3$-norm of initial data is sufficiently small, then the regular solution exists globally in time.

math.AP↗
arXiv2012

Boundary regularity criteria for suitable weak solutions of the magnetohydrodynamic equations

We present some new regularity criteria for suitable weak solutions of magnetohydrodynamic equations near boundary in dimension three. We prove that suitable weak solutions are Hölder continuous near boundary provided that either the scaled $L^{p,q}_{x,t}$-norm of the velocity with $3/p+2/q\le 2$, $2<q<\infty$, or the scaled $L^{p,q}_{x,t}$-norm of the vorticity with $3/p+2/q\le 3$, $2<q<\infty$ are sufficiently small near the boundary.

math.AP↗