- #1
physmatics
- 16
- 0
Homework Statement
Hi!
Not sure if I'm posting in the right section, this problem is from a course in scientific computing. Anyway, we're considering a set of PDEs:
[tex] u_t + Au_x = 0 \quad 0<x<1, \ t>0 \\
u(x,0) = f(x) \quad 0 \leq x \leq1 \\
u_1(0,t) = 0 \quad t \geq 0 \\
u_2(1,t) = 0 \quad t \geq 0 \\
u =
\begin{pmatrix}
u_1 \\
u_2
\end{pmatrix},
\quad A = \begin{pmatrix}
0 & 1 \\
1 & 0
\end{pmatrix}
[/tex]
Now, I want to compute a bound ||u(*, )|| in terms of f. We have the standard inner product and the norm, where ||u||^2 = (u,u).
The Attempt at a Solution
First and foremost, my idea is that I use what's called the energy method, where we multiply with u, integrate in space and apply the BCs, to find ||u||. What I can't wrap my head around though is the fact that A is a matrix and in reality I have two equations, but coupled since they both contain u1 and u2. Should I introduce two variables to multiply the equations with? How can I deal with the matrix while integrating? Or should I just give up the energy method completely and take on another approach?
Any help or small hints are much appreciated!