.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "auto_examples/nonhydro/rayleigh_taylor_instability.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_auto_examples_nonhydro_rayleigh_taylor_instability.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_auto_examples_nonhydro_rayleigh_taylor_instability.py:


Rayleigh-Taylor Instability
===========================

A 2D setup with a denser fluid on top of a lighter fluid.

.. video:: videos/rayleigh_taylor_instability.mp4

.. GENERATED FROM PYTHON SOURCE LINES 10-116







.. code-block:: Python

    import fridom.nonhydro as nh
    import matplotlib.pyplot as plt
    import numpy as np

    # ----------------------------------------------------------------
    #  Experiment settings
    # ----------------------------------------------------------------
    # General settings
    make_video  = True
    fps         = 30
    make_netcdf = True
    run_length  = 10.0
    exp_name    = "rayleigh_taylor_instability"
    thumbnail   = f"figures/{exp_name}.png"

    # Physical parameters
    f0 = 0            # No rotation
    N2 = 0            # No stratification
    Lx = 2            # 2 m in x
    Lz = 1            # 1 m in z

    # Numerical parameters
    resolution_factor = 10           # 2^10 = 1024 grid points
    Nx = 2**(resolution_factor + 1)  # Number of grid points in x
    Nz = 2**resolution_factor        # Number of grid points in z

    # ----------------------------------------------------------------
    #  Create a plotting module for the animation and thumbnail
    # ----------------------------------------------------------------
    class Plotter(nh.modules.animation.ModelPlotter):
        def create_figure():
            return plt.figure(figsize=(8, 3.5), dpi=256, tight_layout=True)

        def prepare_arguments(mz: nh.ModelState) -> dict:
            skip = 30
            return {"z": mz.z.xrs[::skip,0,::skip],
                    "b": mz.z.b.xrs[:,0,:],
                    "t": mz.clock.time}

        def update_figure(fig, z, b, t) -> None:
            import cmocean
            colors = cmocean.cm.ice(np.linspace(0.4, 1, 256))
            cmap = plt.cm.colors.ListedColormap(colors)

            ax = fig.add_subplot(111)
            b.plot(cmap=cmap, vmax=1, vmin=0)
            key = z.plot.quiver("x", "z", "u", "w", scale=100, add_guide=False)
            label_velo = 1
            ax.quiverkey(key, X=0.9, Y=1.05, U=label_velo,
                        label=f'{label_velo} [m/s]', labelpos='E')
            ax.set_aspect('equal')
            ax.set_title(f't={t:.1f}s', fontsize=18)

    # ----------------------------------------------------------------
    #  Main routine
    # ----------------------------------------------------------------
    @nh.utils.skip_on_doc_build
    def main():
        # ----------------------------------------------------------------
        #  Create the grid and model settings
        # ----------------------------------------------------------------
        grid = nh.grid.cartesian.Grid(N=(Nx, 1, Nz), L=(Lx, 1, Lz), 
                                    periodic_bounds=(True, True, False))
        mset = nh.ModelSettings(grid=grid, f0=f0, N2=N2)
        mset.time_stepper.dt = 0.2 / Nz

        # ----------------------------------------------------------------
        #  Add custom modules to the model settings
        # ----------------------------------------------------------------
        mset.tendencies.add_module(nh.modules.closures.SmagorinskyLilly())

        # add a video writer
        if make_video:
            mset.diagnostics.add_module(nh.modules.animation.VideoWriter(
                Plotter, model_time_per_second=1.0, filename=exp_name, fps=fps))

        # create a NetCDF writer to save the output
        if make_netcdf:
            mset.diagnostics.add_module(nh.modules.NetCDFWriter(
                write_trigger = nh.ClockTrigger(time_interval=0.2),
                filename=exp_name))

        # create a thumbnail saver
        mset.diagnostics.add_module(nh.modules.FigureSaver(
            filename=thumbnail, model_time=4, plotter=Plotter))

        mset.setup()
        # ----------------------------------------------------------------
        #  Create the initial condition
        # ----------------------------------------------------------------
        z = nh.State(mset)
        # add some white noise to the initial condition so that the
        # instabilities are triggered
        z.b.arr += (z.b.get_mesh()[2] < 0.5)
        z.u.arr += nh.utils.random_array(z.u.arr.shape) * 1e-6

        # ----------------------------------------------------------------
        #  Run the model
        # ----------------------------------------------------------------
        model = nh.Model(mset)
        model.z = z
        model.run(runlen=run_length)
        return model

    if __name__ == "__main__":
        model = main()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.815 seconds)


.. _sphx_glr_download_auto_examples_nonhydro_rayleigh_taylor_instability.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: rayleigh_taylor_instability.py <rayleigh_taylor_instability.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: rayleigh_taylor_instability.zip <rayleigh_taylor_instability.zip>`