This is adding a new 2D vortex example to PyClaw notebooks. This is example 2.2 in the paper https://www.global-sci.org/v1/cicp/issue/FULLPDF/9/807/paper.pdf?code=5PGikBxEljgnVQwsaSy7Hg%3D%3D . It demonstrates how to solve the 2D Euler equations for compressible gas dynamics with periodic boundary conditions and perturbations to the mean flow. This notebook compares the performance between classical Clawpack and SharpClaw WENO solvers. The problem is initiated in the issue clawpack/pyclaw#714.

This changed the discrete L1-norm to continuous L1-norm for computing the error.

Compared to the previous one, this file adds a new example which compares the performance of Clawpack with SharpClaw on a vortex moving a small time.