{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# Oil film thickness\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "from datetime import datetime, timedelta\nimport matplotlib.pyplot as plt\nimport numpy as np\nfrom opendrift.models.openoil import OpenOil\n\n\nnumber = 10000\ntimestep = timedelta(minutes=10)\ntimestep_output = timedelta(minutes=60)\nduration = timedelta(hours=20)\nmass_oil = 2000  # mass oil per particle\noil_type = 'GENERIC DIESEL'\n#oil_type = 'GENERIC BUNKER C'"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "First run, where surface oil thickness is updated\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "o1 = OpenOil(loglevel=20, weathering_model='noaa')"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Northwards wind, eastwards current\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "o1.set_config('environment:fallback:land_binary_mask', 0)\no1.set_config('environment:fallback:x_wind', 0)\no1.set_config('environment:fallback:y_wind', 7)\no1.set_config('environment:fallback:sea_surface_wave_stokes_drift_x_velocity', 0)\no1.set_config('environment:fallback:sea_surface_wave_stokes_drift_y_velocity', .3)\no1.set_config('environment:fallback:x_sea_water_velocity', .1)\no1.set_config('environment:fallback:y_sea_water_velocity', 0)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Using Johansen droplet spectrum, which depends on oil film thickness\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "o1.set_config('wave_entrainment:droplet_size_distribution',\n             'Johansen et al. (2015)')\no1.set_config('drift:wind_uncertainty', 2)\no1.set_config('drift:current_uncertainty', .1)\no1.set_config('processes:dispersion', False)\no1.set_config('processes:update_oilfilm_thickness', True)\n\no1.seed_elements(lon=4.5, lat=60, number=number,\n                mass_oil=mass_oil, radius=1000,\n                oil_type=oil_type,\n                time=datetime.utcnow())\no1.run(time_step=timestep, time_step_output=timestep_output,\n       duration=duration)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Animation shows how oil thickness evolves,\nand decreases due to evaporation and spreading\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "unitfactor=1e6  # show film thickness in micrometers\no1.animation(color='oil_film_thickness', fast=True,\n             vmin=1e-7*unitfactor, vmax=1e-4*unitfactor,\n             unitfactor=unitfactor, surface_only=True)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "<img src=\"file://gallery/animations/example_oil_thickness_0.gif\">\n\n"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Second run, identical but without updating surface oil thickness\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "o2 = OpenOil(loglevel=20, weathering_model='noaa')\no2.set_config('environment:fallback:land_binary_mask', 0)\no2.set_config('environment:fallback:x_wind', 0)\no2.set_config('environment:fallback:y_wind', 7)\no2.set_config('environment:fallback:sea_surface_wave_stokes_drift_x_velocity', 0)\no2.set_config('environment:fallback:sea_surface_wave_stokes_drift_y_velocity', .3)\no2.set_config('environment:fallback:x_sea_water_velocity', .1)\no2.set_config('environment:fallback:y_sea_water_velocity', 0)\n\no2.set_config('wave_entrainment:droplet_size_distribution',\n             'Johansen et al. (2015)')\no2.set_config('drift:wind_uncertainty', 2)\no2.set_config('drift:current_uncertainty', .1)\no2.set_config('processes:dispersion', False)\no2.set_config('processes:update_oilfilm_thickness', False)\n\no2.seed_elements(lon=4.5, lat=60, number=number,\n                mass_oil=mass_oil, radius=1000,\n                oil_type=oil_type,\n                time=datetime.utcnow())\no2.run(time_step=timestep, time_step_output=timestep_output,\n       duration=duration)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Comparison plots\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "o1.plot_oil_budget()\no2.plot_oil_budget()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Entrainment\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "b1 = o1.get_oil_budget()\nb2 = o2.get_oil_budget()\nplt.plot(b1['mass_surface'], '-r', linewidth=2,\n            label='Surface, updated thickness')\nplt.plot(b1['mass_submerged'], '--r', linewidth=2,\n            label='Submerged, updated thickness')\nplt.plot(b1['mass_evaporated'], '-.r', linewidth=2,\n            label='Evaporated, updated thickness')\nplt.plot(b2['mass_surface'], '-b', linewidth=2,\n            label='Surface, constant thickness')\nplt.plot(b2['mass_submerged'], '--b', linewidth=2,\n            label='Submerged, constant thickness')\nplt.plot(b2['mass_evaporated'], '-.b', linewidth=2,\n            label='Evaporated, constant thickness')\nplt.legend()\nplt.xlabel('Time step')\nplt.show()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "We see that with the updated film thickness,\nthe droplets are getting gradually smaller\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "r1 = o1.get_property('diameter')[0]\nr2 = o2.get_property('diameter')[0]\nplt.plot(np.median(r1*1e6, 1))\nplt.plot(np.median(r2*1e6, 1))\nplt.legend(['With updated film thickness', 'With constant film thickness'])\nplt.xlabel('Time step')\nplt.ylabel('Median droplet diameter  [micrometer]')\nplt.show()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "We see that oil film thickness has virtually no impact on horizontal drift\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "o1.animation(compare=o2, fast=True,\n             legend=['Updated film thickness',\n                     'Constant/default film thickness'])"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "<img src=\"file://gallery/animations/example_oil_thickness_1.gif\">\n\n"
      ]
    }
  ],
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