Analysis of 2+1 diffusive-dispersive PDE arising in river braiding

TL;DR

This paper establishes local existence, uniqueness, and global energy bounds for a 2+1 dispersive-diffusive PDE modeling river braiding, using Bourgain spaces and contraction mapping techniques.

Contribution

It provides the first rigorous analysis of a 2+1 diffusive-dispersive PDE in river modeling, demonstrating well-posedness and energy control.

Findings

Proved local existence and uniqueness of solutions.

Established global bounds on energy and dissipation.

Applied Bourgain space techniques to a river braiding PDE.

Abstract

We present local existence and uniqueness results for the following $2+1$ dispersive diffusive equation due to P. Hall arising in modeling of river braiding: $$u_{yyt} - \gamma u_{xxx} -\alpha u_{yyyy} - \beta u_{yy} + \left (u^2 \right)_{xyy} = 0$$ for $(x,y) \in [0, 2\pi] \times [0, \pi]$, $t> 0$, with boundary condition $u_{y}=0=u_{yyy}$ at $y=0$ and $y=\pi$ and $2\pi$ periodicity in $x$, using a contraction mapping argument in a Bourgain-type space $T_{s,b}$. We also show that the energy $\| u \|^2_{L^2} $ and cumulative dissipation $\int_0^t \| u_y \|_{L^2}^2 dt$ are globally controlled in time.