#!/usr/bin/env python
# encoding: utf-8

"""
2D Euler Riemann problem
================================

Solve the Euler equations of compressible fluid dynamics:

.. math::
    \rho_t + (\rho u)_x + (\rho v)_y & = 0 \\
    (\rho u)_t + (\rho u^2 + p)_x + (\rho uv)_y & = 0 \\
    (\rho v)_t + (\rho uv)_x + (\rho v^2 + p)_y & = 0 \\
    E_t + (u (E + p) )_x + (v (E + p))_y & = 0.

Here :math:`\rho` is the density, (u,v) is the velocity, and E is the total energy.
The initial condition is one of the 2D Riemann problems from the paper of
Liska and Wendroff.

This example shows how to use VisClaw's Iplot class for simple interactive plotting.
"""
from __future__ import absolute_import
from clawpack import pyclaw
from clawpack import riemann
from clawpack.riemann.euler_4wave_2D_constants import density, x_momentum, y_momentum, \
        energy, num_eqn

def load_frame(frame_number):
    from clawpack.pyclaw import Solution

    return Solution(frame_number)

def plot_frame(frame):
    import matplotlib.pyplot as plt
    q = frame.q
    x, y = frame.state.grid.c_centers
    plt.pcolormesh(x, y, q[density,...])

def plot_results():
    from clawpack.visclaw import iplot
    ip = iplot.Iplot(load_frame,plot_frame)
    ip.plotloop()

solver = pyclaw.ClawSolver2D(riemann.euler_4wave_2D)
solver.all_bcs = pyclaw.BC.extrap

domain = pyclaw.Domain([0.,0.],[1.,1.],[200,200])
solution = pyclaw.Solution(num_eqn,domain)
gamma = 1.4
solution.problem_data['gamma']  = gamma

# Set initial data
xx,yy = domain.grid.p_centers
l = xx<0.5; r = xx>=0.5; b = yy<0.5; t = yy>=0.5
solution.q[density,...] = 2.*l*t + 1.*l*b + 1.*r*t + 3.*r*b
solution.q[x_momentum,...] = 0.75*t - 0.75*b
solution.q[y_momentum,...] = 0.5*l  - 0.5*r
solution.q[energy,...] = 0.5*solution.q[density,...]*(solution.q[x_momentum,...]**2+solution.q[y_momentum,...]**2) + 1./(gamma-1.)

claw = pyclaw.Controller()
claw.tfinal = 0.3
claw.solution = solution
claw.solver = solver

status = claw.run()

#plot_results()
