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Feb 26 2024

# Analysis and Applied Mathematics Seminar: On Some Joint Effects of Dispersion and Dissipation of a Class of Nonlinear Evolution Equations, by Bingyu Zhang.

February 26, 2024

4:00 PM - 4:50 PM

636 SEO

Chicago, IL

## Calendar

Bingyu Zhang. (U. of Cincinnati): On Some Joint Effects of Dispersion and Dissipation of a Class of Nonlinear Evolution Equations

It is known that the solutions of the Cauchy problem for the Korteweg-de Vries (KdV) equation
$u_t +uu_x +u_{xxx} =0, \quad u(x,0)= \phi (x), \quad x\in T, \ t\in R,$

and the viscous Burgers equation

$u_t +uu_x - u_{xx} =0, \quad u(x,0)= \phi (x), \quad x\in T, \ t>0$

posed on a periodic domain $T$, do not possess the sharp Kato smoothing property:

$\phi \in H^s (T) \implies \partial ^{s+1}_xu \in L^{\infty}_x (T, L^2 (0,T))$.

Here, we discuss the equation,

$u_t +uu_x +\alpha (x,t) u_{xxx} - \beta (x,t)u_{xx} =0, \qquad u(x,0)= \phi (x), \quad x\in T, \ t\geq 0,$

and demonstrate that if

$\int _{\mathbb{T}}\frac{\beta (x,t)}{|\alpha (x,t)|} dx >0 \quad \forall t\geq 0,$

and if it is locally well-posed in the space $H^s (T)$ with $s \geq 0$,
then its solution $u$ possesses the sharp Kato smoothing property,

$\phi \in H^s (T) \implies \partial ^{s+1}_xu \in L^{\infty}_x (T, L^2 (0,T)), \quad \forall \, s\geq 0.$

In addition, the nonlinear part of its solution $u$ possesses the strong Kato smoothing property,

$\phi \in H^s (T) \implies (u -v)\in C([0,T]; H^{s+1} (T)), \quad \forall \, s>\frac12,$

and the double sharp Kato smoothing property

$\phi \in H^s (T) \implies \partial ^{s+2}_x(u -v)\in L^{\infty}_x (\T, L^2 (0,T)), \quad \forall \, s>\frac12,$

with $v$ being the solution of the linear problem

$v_t+ \alpha (x,t)v_{xxx} - \beta (x,t) v_{xx} =0, \quad v(x,0)=\phi (x), \quad x\in T, \ t>0.$

Jerry Bona

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