Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options questions only not deleted user 80602

Questions about partial differential equations of hyperbolic type. Often used in combination with the top-level tag ap.analysis-of-pdes.

3 votes
0 answers
124 views

Wave equation that becomes elliptic on a bounded domain (sign-changing coefficient)

I'm looking for results on this kind of problems: $$ \partial_{tt}^2 u - \partial_x(a(x) \partial_x) = f,$$ $$u(t=0) = u_0, \quad \partial_t u(t=0) = u_1,$$ where $a$ changes sign: $a(x)= -c^2 < 0$ fo …
Héhéhé's user avatar
  • 615
3 votes
1 answer
398 views

Does Huygens principle holds for heterogeneous media (variable coefficients)?

I'm having trouble to find references on that. Consider for instance a very simple model of a wave equation with variable coefficients: $$\partial_{tt}^2 u(x,t) - \nabla \cdot( a(x) \nabla u(x,t)) = f …
Héhéhé's user avatar
  • 615