"""A RT problem with two distinct modes: short wavelength on the
left and long wavelength on the right.  This allows one to see
how the growth rate depends on wavenumber.
"""

import numpy as np

from pyro.util import msg

DEFAULT_INPUTS = "inputs.rt2"

PROBLEM_PARAMS = {"rt2.dens1": 1.0,
                  "rt2.dens2": 2.0,
                  "rt2.amp": 1.0,
                  "rt2.sigma":  0.1,
                  "rt2.p0": 10.0}



[docs]
def init_data(my_data, rp):
    """ initialize the rt problem """

    if rp.get_param("driver.verbose"):
        msg.bold("initializing the rt problem...")

    # get the density, momenta, and energy as separate variables
    dens = my_data.get_var("density")
    xmom = my_data.get_var("x-momentum")
    ymom = my_data.get_var("y-momentum")
    ener = my_data.get_var("energy")

    gamma = rp.get_param("eos.gamma")

    grav = rp.get_param("compressible.grav")

    dens1 = rp.get_param("rt2.dens1")
    dens2 = rp.get_param("rt2.dens2")
    p0 = rp.get_param("rt2.p0")
    amp = rp.get_param("rt2.amp")
    sigma = rp.get_param("rt2.sigma")

    # initialize the components, remember, that ener here is
    # rho*eint + 0.5*rho*v**2, where eint is the specific
    # internal energy (erg/g)
    xmom[:, :] = 0.0
    ymom[:, :] = 0.0
    dens[:, :] = 0.0

    f_l = 18
    f_r = 3

    # set the density to be stratified in the y-direction
    myg = my_data.grid

    ycenter = 0.5*(myg.ymin + myg.ymax)

    p = myg.scratch_array()

    j = myg.jlo
    while j <= myg.jhi:
        if myg.y[j] < ycenter:
            dens[:, j] = dens1
            p[:, j] = p0 + dens1*grav*myg.y[j]

        else:
            dens[:, j] = dens2
            p[:, j] = p0 + dens1*grav*ycenter + dens2*grav*(myg.y[j] - ycenter)

        j += 1

    idx_l = myg.x2d < (myg.xmax - myg.xmin)/3.0
    idx_r = myg.x2d >= (myg.xmax - myg.xmin)/3.0

    ymom[idx_l] = amp*np.sin(4.0*np.pi*f_l*myg.x2d[idx_l] /
                             (myg.xmax-myg.xmin))*np.exp(-(myg.y2d[idx_l]-ycenter)**2/sigma**2)
    ymom[idx_r] = amp*np.sin(4.0*np.pi*f_r*myg.x2d[idx_r] /
                             (myg.xmax-myg.xmin))*np.exp(-(myg.y2d[idx_r]-ycenter)**2/sigma**2)

    ymom *= dens

    # set the energy (P = cs2*dens)
    ener[:, :] = p[:, :]/(gamma - 1.0) + \
        0.5*(xmom[:, :]**2 + ymom[:, :]**2)/dens[:, :]




[docs]
def finalize():
    """ print out any information to the user at the end of the run """