"""A single-mode Rayleigh-Taylor instability."""

import numpy as np

from pyro.util import msg

DEFAULT_INPUTS = "inputs.rt"

PROBLEM_PARAMS = {"rt.dens1": 1.0,
                  "rt.dens2": 2.0,
                  "rt.amp": 1.0,
                  "rt.sigma": 0.1,
                  "rt.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("rt.dens1")
    dens2 = rp.get_param("rt.dens2")
    p0 = rp.get_param("rt.p0")
    amp = rp.get_param("rt.amp")
    sigma = rp.get_param("rt.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

    # 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

    L = myg.xmax-myg.xmin
    ymom[:, :] = amp * 0.5 * (np.cos(2.0*np.pi*myg.x2d/L) +
                              np.cos(2.0*np.pi*(L - myg.x2d)/L)) * np.exp(-(myg.y2d-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 """