## Advances in Differential Equations

- Adv. Differential Equations
- Volume 20, Number 11/12 (2015), 1033-1066.

### Local and global estimates of solutions of Hamilton-Jacobi parabolic equation with absorption

#### Abstract

Here, we show new apriori estimates for the nonnegative solutions of the equation \[ u_{t}-\Delta u+|\nabla u|^{q}=0, \] in $Q_{\Omega,T}=\Omega\times\left( 0,T\right) ,$ $T\leqq\infty,$ where $q > 1,$ and $\Omega=\mathbb{R}^{N},$ or $\Omega$ is a smooth bounded domain of $\mathbb{R}^{N}$ and $u=0$ on $\partial\Omega\times\left( 0,T\right) .$ In case $\Omega=\mathbb{R}^{N},$ we show that any solution $u\in C^{2,1}(Q_{\mathbb{R}^{N},T})$ of equation $(1.1)$ in $Q_{\mathbb{R}^{N}% ,T}$ (in particular, any weak solution if $q\leqq2),$ without condition as $\left\vert x\right\vert \rightarrow\infty,$ satisfies the universal estimate \[ \left\vert \nabla u(x,t)\right\vert ^{q}\leqq\frac{1}{q-1}\frac{u(x,t)}% {t}\qquad\text{in }Q_{\mathbb{R}^{N},T}. \] Moreover, we prove that the growth of the solutions is limited in space and time: \[ u(x,t)\leqq C(t+t^{-1/(q-1})(1+\left\vert x\right\vert ^{q^{\prime}}% )\qquad\text{in }Q_{\mathbb{R}^{N},T}, \] where $C$ depends on the initial data. We also give existence properties of solutions in $Q_{\Omega,T},$ for initial data locally integrable or unbounded measures. We give a nonuniqueness result in case $q > 2.$ Finally, we show that besides the local regularizing effect of the heat equation, $u$ satisfies a second effect of type $L_{loc}^{R}% $-$L_{loc}^{\infty},$ due to the gradient term.

#### Article information

**Source**

Adv. Differential Equations Volume 20, Number 11/12 (2015), 1033-1066.

**Dates**

First available in Project Euclid: 18 August 2015

**Permanent link to this document**

https://projecteuclid.org/euclid.ade/1439901070

**Mathematical Reviews number (MathSciNet)**

MR3388892

**Zentralblatt MATH identifier**

1334.35150

**Subjects**

Primary: 35K15: Initial value problems for second-order parabolic equations 35K55: Nonlinear parabolic equations 35B33: Critical exponents 35D30: Weak solutions 35D30: Weak solutions

#### Citation

Bidaut-Veron, Marie Françoise. Local and global estimates of solutions of Hamilton-Jacobi parabolic equation with absorption. Adv. Differential Equations 20 (2015), no. 11/12, 1033--1066. https://projecteuclid.org/euclid.ade/1439901070