Mathematical Modeling and Forecasting the Spread of an Oil Spill
using Python
NIKOLAOS KASTROUNIS1, GEORGE MANIAS2, MICHAEL FILIPPAKIS2,
DIMOSTHENIS KYRIAZIS2
1Department of Mechanical Engineering, Frederick University, Nicosia 1036, CYPRUS
2Department of Digital Systems, University of Piraeus, Piraeus, GREECE
Abstract: This is a comprehensive paper on the oil spill phenomenon on what mechanisms change the oil spill
displacement, what Computational Fluid Dynamic (CFD) applications of Finite Volume and
Eulerian/Lagragian equations are used to solve oil-spill simulations and to provide a brief analysis of the
models used. An oil spill is defined as a form of pollution caused by human activity and as the discharge of
liquid petroleum hydrocarbons into the environment, mainly in the marine eco-system. This description is
commonly used for marine oil spills, where the hydrocarbons are discharged into the ocean or coastal waters,
but they can also occur inland. Oil spills occur because of discharges of hydrocarbons from platforms, rigs,
wells, tankers and from refined petroleum products along with their by-products, also from heavier fuels. Thus,
oil spill simulation is used to predict transport and weathering processes. State-of-the-art tools such as
OILMAP, TRANSAS, OILFLOW2D, OSCAR and ANSYS, work by simulating the processes mentioned
prior. In contrary to these tools, the aim of this paper is to provide a comparison of the weathering models used
and propose a mathematical model using python to predict the spreading phenomenon of an oil spill.
Key-Words: Fate/Weathering Processes, Oil Spill, Simulation/Modeling
Received: June 19, 2021. Revised: June 26, 2022. Accepted: July 19, 2022. Published: September 22, 2022.
1 Introduction
The proposed mathematical model used for the
purpose of this experiment and paper only tackles the
spreading aspect of a spill without taking into account
wind/wave parameters using python programming
language, but it also enables a future use of CUDA
GPU (graphics processing unit) which will greatly
increase processing speed.
Oil spills are a matter of serious concern due to
their damaging nature. Due to the constantly
changing conditions in the sea/ocean, the physical
processes acting on a spill change. There are a
number of ways to counter the negative impact of an
oil spill in the sea, such as: skimmers, booms and
chemical dispersants. One way of tracking oil spills is
the use of numerical models [1]-[4]. The forecast of
the oil slick movement relies upon the availability of
dependable ocean estimates. Oil slicks are carried
away by two systems correlated with mass. The
initial spread of the slick is due to the force of
gravity. The effects of gravitational forces tend to
fade an hour after the start of the spill, (increase of
viscosity, and decrease in thickness); it is then that
diffusion starts to be the dominant mechanism in the
oil spill movement [1], [2].
Crucial environmental data for oil spill modelling
are: the wind, the sea currents, waves (Stoke’ drift)
and sea surface temperature. The water density is
used in 3D oil spill models when the spill is below
the sea [3]. Accessible data at all times for any
occasion/circumstance that may be needed for oil
spill models is now available for the requirements of
the Oceanographic predicting systems (CMEMS,
NOAA) [4]. It is fundamental to have admission to an
adequate estimation of ocean conditions and
information crucial to modelling, in order to provide
response to oil spill crises [2].
Social, economic and environmental consequences
of an oil spill are detrimental. As an outcome, the
responsibility of governments was raised by the acute
media coverage and political commotion, leading to a
political attempt to engage reactions to oil spills and
provide prevention methods [5], [6]. Oil related
disasters can have economic impacts on tourism and
in the marine industry, such as the Deepwater
Horizon incident. The flora and fauna of the area are
also affected. This is done either directly from the
response or during the cleanup. Oil can impair the
ability of animals to fly, use their scent, or it can even
cause blindness. Oil bacteria; Sulphate-reducing
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Nikolaos Kastrounis, George Manias,
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bacteria, acid-producing bacteria and general aerobic
bacteria consumption play the role of natural
ecosystem oil removals. But due to the amount of oil
present their mass will replace other biomasses in the
food chain [1], [8]. Clean-up and recovery can prove
to be a difficult task. However, the process depends
on some factors: such as type of oil, temperature and
or shoreline topography. Oil spill recovery is often an
expensive procedure [9], [10]. Notable methods
include the use of micro-organisms, dispersants,
control burning, dredging, skimming, solidifying,
vacuuming, beach raking and just waiting for natural
attenuation [10], [27].
The remainder of this paper is structured as
follows. Section 2 describes the related work in the
form of a literature review and the models that have
been utilized. While in Section 3 the oil weathering
process is being introduced and analyzed.
Afterwards, Section 4 presents the experimental
results and the visualization approach that was
followed to demonstrate the oil spilling through the
utilization of machine learning and time series
analysis techniques. Moreover, Section 5 discusses
the experimental results. Finally, Section 6 concludes
the paper and outlines some directions for future
works and further enhancements on the proposed
methodology.
2 Related Work - Background
Taking into account the points mentioned above,
engineering software is used to model oil spill by
simulating the oil processes. Quoting Spaulding ML.
“Current fields are generally considered to be the
vectoral sum of wind, tidal density, and pressure
gradient induced currents. Of these various
components, the wind-induced drift is often the most
important factor determining surface oil slick
trajectories over time scales greater than 1 day. The
extremely simple empirical approach, which assumes
surface drift current is approximately 3-4% of the
wind speed, has been used by most existing models
and continues to be the most widely accepted
methodology. Samuels et al. suggest a variable drift
angle depending on wind speed, although a constant
angle between 0 and 20 o, typically 10-17 °, is more
common. This simplistic approach gives acceptable
results if the study area does not include conditions in
which coastal or bathymetric effects are dominant; in
these cases wind-driven currents become much more
complex (e.g. Spaulding et al.)” [1], [11].
Drifting occurs when materials are carried in the
sea. The process relies on the sea status, such as
wind, current and waves. Oil properties will change
as it spreads when it is spilled. The time it takes for
the spill to adapt to these changes that occur (to the
spill) being chemical or physical, depends on the
initial amount of oil spilled, as well as the oceanic
conditions present and the characteristics of the oil.
Thus, it is important for all the facet of the oil
recovery process to know how the synergy of the
physical and chemical processes change the balance
and presence of oil.
Langrangian or Eulerian models are usually applied
when modelling oil movement. Conservation of mass
and momentum equations are utilized on the oil spill
for the Eulerian method, or convection diffusion,
where the spreading of the oil is presented by the
diffusive part while the advection is the convective
term [1], [2].
2 2 2
2 2 2
x y z
C C C C C C C
u D v D w D
t x x y y z z
(1)
The time rate of concentration change is ∂C/∂t, x,
y, z are the changes in the respective axis, current
components u, v, w are the current components and D
is the diffusive displacement.
On the other hand, a large number of particles
advected due to the united effect of sea phenomena
(such as wind, wave, currents, etc.) and diffusion are
depicted by the Lagrangian models. By being more
straightforward, more potent and requiring less
computational processing power during a spill
emergency, Lagragian models are commonly
favoured over Eulerian ones due to rapid simulations.
Since the early 80s a lot of Lagrangian models have
been developed featuring from 2D (two dimensional)
particle tracking to 3D (three dimensional) advection
diffusion models. Some notable mentions include:
OSCAR2000 [12], OILMAP [11], GNOME [13],
OILTRANS [13]-[14]. Oil-spill models are defined as
scientific means, suitable of estimating the path of an
oil spill (1), the time it takes to reach certain
modelled points (2), and the state in which it will be
once it reaches the said points (3). Points one (1) and
two (2) call for precise data on winds, currents and
waves in the wider vicinity of the oil spill incident,
while the third (3) one needs knowledge and
algorithms of oil-weathering-processes [14].
Precise forecasting of transport fate and weathering
processes of the oil spill pose a challenge due to the
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complexity of the oil interaction with the marine
environment. In this review they are categorized in
Operational Response Models and Deep-Sea
Blowout/Buoyant [14].
Operational Response Models can compute all of
the essential transport, fate/weathering processes. The
aim of the operational response models is to provide
support in case of an oil spill by predicting the
transport/fate of the oil spill [14]. Deep-Sea
Blowout/Buoyant Models can compute simulations of
spills originating from the sea bed or other depths and
they rely on complicated physio-chemical processes
[14], [25].
Below is a table, Table 1, illustrating the
aforementioned software packages and their
respective modelling capabilities (features and
processes) categorized in Operational Response and
Deep-sea Blowout [14].
Table 1. - Weathering Models Features and
Processes Quoting Zodiatis G, Lardner R, Alves TM,
Krestenitis Y, Perivoliotis L, Sofianos S, et al. Oil
spill forecasting (prediction). Journal of Marine
Research. 2017;75:923-53. [28-29]
Features/Proc
esses
DEEP SEA
BLOWOUT/BUOYA
NT
GNOME
MOTHY
POSEIDON-OSM
MEDSLIK
MEDSLIK-2
OpenOil
OSCAR
SIMAP
OILMAP
MOHID
OILTRANS
OSERIT
OILTOX
DELFT3D-PART
CDOG
OILMAPDEEP
TAMOC
BLOSOM
General Features/Application
Open source
coding
×
×
×
×
×
×
×
Weathering/Fate
model
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Lagrangian
model
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Transport model
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Near-field plume
×
×
×
×
×
×
×
Far-field
transition
×
×
×
×
×
×
×
Surface-oil
model
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Blowout/buoyant
plume model
×
×
×
×
×
×
×
×
Back-tracking
×
×
×
×
×
×
×
×
×
×
Stochastic
element
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Random-walk
scheme
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Oil data-base
×
×
×
×
×
×
×
×
Bathymetric data
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Response
assistance
×
×
×
×
×
×
×
×
×
×
×
×
×
Environmental
impact
×
×
×
×
×
Injury
assessment
×
×
×
×
Research
×
×
×
×
×
×
×
×
×
×
×
Transport
/Weatheri
ng
processes
Advection
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Spreading
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Diffusion
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Beaching
×
×
×
×
×
×
×
×
×
×
×
×
×
×
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Dispersion/Entra
inment
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Evaporation
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Emulsification
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Dissolution
×
×
×
×
×
×
×
Sedimentation
×
×
×
×
×
×
×
×
×
×
×
Bio-degradation
×
×
×
×
Wind drift
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Vertical
turbulent mix
×
×
×
×
×
×
×
×
×
×
×
×
Resurfacing
×
×
×
×
×
×
Stokes drift
×
×
×
×
×
×
×
×
×
×
Photo-oxidation
×
Oil Spill Contingency and Response or
OSCAR2000, is a state of the art three (3)
dimensional dynamic oil simulation package. It
predicts the fate, recovery and processes of oil or gas.
The processes at the surface i.e., wind, diffusion,
currents and wind are expressed as algorithms i.e.
spreading, evaporation, dispersion. As a decaying
first order processes the degradation and
sedimentation are described. OSCAR2000 has been
widely used as a response (planning and operation) as
well as a spill rick estimate package [12], [14].
OILMAP is a three (3) dimensional modelling
package that can predict oil movement. It can predict
surface and sub-surface oil discharges, while its
modelling package is used for spreading, evaporation,
emulfication ,entrainment etc.[11], [14]
General NOAA Operational Modelling
Environment or GNOME is an oil spill model that
predicts the fate and transport due to wind, current,
tide and spreading. GNOME is capable of supporting
three-dimensional molecule transits; ability to process
any hydro-dynamic model and data; grow wind
surface transfer; it has open-source coding
capabilities; and many more. Furthermore, it is very
adjustable, able to apply any oil-field environment
and can be compelled by an abundance of data such
as: evaluated point data, models, and meshes [13],
[14].
OILTRANS model is established on the LTRANS
molecule transference model. OILTRANS is a state-
of-the-art model that replicates the fate, transport and
oil weathering processes [14], [15].
OpenDrift and OpenOil. OpenOil is a python
open-source transport and fate module (drift) build on
OpenDrift.
Blowout and spill occurrence or BLOSOM, is a
java model and is used to model the fate and transport
of surface and subsurface oil spills. BLOSOM is also
capable of anticipating off-shore oil-spills emerging
from deep water (>150m and >1500m) blowouts.
BLOSOM reproduces oil spill incidents from the start
of the spill to the fate and de-gradation point [14].
Delft3D-PART is a component of Delft3D, that
predicts oil transport via a molecule tracking method.
Delft3D-PART offers two components; a tracer one
and the oil spill which focuses on transport and
dispersion [14].
OSERIT is an evaluation and response component.
It can forecast the drift and fate of the oil-spill and its
dispersion into the water column. OSERIT can
compile oil weathering processes such as: diffusion,
dispersion, spreading and beaching amongst others
[14].
Modele oceanique de transport d’hydrocarbures or
MOTHY, is a 3D-Langrangian model, which
forecasts the fate and transport of oil-slicks. It can
simulate shallow water with wind, pressure and
turbulent viscosity processes, along with turbulent
diffusion.[14]
OILTOX is also a Lagrangian oil-spill model
which can predict the following processes; transport
and fate such as: spreading, advection, evaporation,
emulsification, entrainment, sedimentation and
diffusion [14].
Modelo Hidrodinamico or MOHID, is a
Lagrangian oil-spill model that simulates the
transport and fate processes of an oil spill such as:
sedimentation, beaching, evaporation, dispersion,
entrainment, sedimentation, dissolution,
emulsification and dispersion respectively [14].
POSEIDON OSM is an oil spill model capable of
simulating the following processes: transport,
spreading, weathering, beaching, sedimentation,
advection and dispersion [14].
SIMAP is a Lagrangian three-dimensional oil spill
model. It can simulate fate and transport of an oil
slick. Some of the processes it can model are:
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dissolution, sedimentation, evaporation, dispersion,
spreading, sedimentation and beaching [14].
TAMOC is an open-source oil spill model capable
of processing dissolution, particle tracking, transport
and plume dynamics of an oil slick [14].
OILMAPDEEP is capable of estimating the fate
processes and transport of sub-surface spills [14].
Comprehensive Deepwater oil and gas model or
CDOG is a three-dimensional oil spill model used for
deep-water spills. Using hydro and thermos dynamics
it can simulate disintegration, gas dissolution and
partition. It can process ambient current, density
stratification, salinity and water temperature [14].
Weathering, spreading, advection, and diffusion
instead of dissolution, photo-oxidation and or
decomposition are processes most models use, using
experimental relationships [15]. Discrete physical
mechanisms produce aside from advection caused by
wind, currents, drift and displacements, time-
susceptible variations. Gravity is the first force that
acts on a slick after an incident occurs, making the
slick spread over an area, with individual particles
spreading. With the volume of oil being reduced due
to the evaporation of lighter oil, the reminder is either
absorbed or emulsified. Those changes are considered
as oil spill property changes. By breaking down the
main spill into various others instead of a whole one,
for each time step, the computer models calculate the
fate processes affecting the oil spill. These processes
are autonomous for each sub spill. Mackay’s adjusted
model is the one commonly used for evaporation,
dispersion and emulsification [16]. According to
Makay, the oil slick is divided into a thick part near
the middle and thin parts (sheen) around the edges.
Quoting Zodiatis, Oil spill forecasting (prediction)
“The sheen is very thin, generally of the order of 10
microns, whereas the thick slick may, in the case of a
large spill, be initially several centimeters thick. Flow
of oil from the thicker core feeds the thinner parts.
Evaporation and dispersion both occur much more
rapidly from the thin sheen than from the thick areas
and these processes are modelled differently for two
components of the s lick” [2].
Oil spill variables needed for models include: type
of oil, location, amount released etc. The tracer
equation (seen below) is used for Lagrangian models
[22], [23],
1 1 1
1
M
j
j
CU C K C r C
t
(2)
Where, the rate of time of oil concentration change,
current U, turbulent effects K (diffusivity tensor), oil
con transformation rate (M) due to processes
(chemical, physical) [2]. The equation above
(Lagrangian tracer equation), is split into two:
Advection/Diffusion equation:
11
CU C K C
t
(3)
Where currents, waves and other processes acting
on the spill and transporting a number of particles are
represented by.
Fate Weathering transformation:
1
1
1
M
j
j
CrC
t
(4)
where C1 is the oil concentration due to the
changes occurring.
Drift flow, resistance due to wind and wave forces
that cause a spill to drift on the surface are the major
forces inflicted on oil spills. Wave movement causes
the submersion of oil particles at the uppermost-sub
surface, while the wind’s magnitude preponderates
the evaporation. In order for the response oil system
models to be successful they require the feasibility of
viable ocean data in order to anticipate oil slick
movement.
Wind is a force moving currents in the water, as
well as moving slicks on the surface of the sea, thus
making it a sovereign element when predicting oil
spill presence in the sea. The wind factor approach is
what most oil spill models are based on, claiming that
wind force will drive the oil spill at a specific fraction
of the speed of the wind and at a specific angle to
wind direction. Drift factor and angle are much
disputed topics regarding oil modelling. For the drift
factor the most common value used is 3 (three) %
while for the angle, it is between 0-30 (zero thirty)
o. This method does have a flaw because in some
cases the effect of currents is calculated twice. As
mentioned by De Dominicis et al., drift caused by
wind related actions has a variety of ways to be dealt
with despite those models being convoluted. A first
choice is to pick current velocity at an average depth.
Another possible solution would be to reduce the drift
factor. And finally one could use the values of wind
to compute sea current flow to reduce effective wind
data to compute drift [12], [17].
The most common walkthrough used in models is
to completely ignore wind and rather use buoyancy.
This way the current effects will not be counted
twice, as the drift factor will be in relation to water.
As mentioned beforehand, the force of wind also
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effects the movement of the oil slick as it pushes the
slick with a fraction α of the speed at an angle β.
cos sin , sin cos
w x y w x y
aa
U W W V W W
(5)
Where Wx and Wy are wind Velocity comp. α and
β are the percentage of wind added to current velocity
and the deviation angle respectively.
The local sea currents consist of smaller
Lagrangian parcels, at which the impact of the wave-
caused currents are considered by Stokes drift
velocity. This is due to the fact that particles move
slower going backwards at the “base” of a wave
rather than going fast in an oblique movement at the
top of a wave. The significant height (Hs), wave (0)
traverse time (Tz) and water extent (z) are used to
compute Stokes drift velocity (S) as shown below,
2
1
,8
xy kd
SS H
(6)
Where k is the wave number, ω the angular
frequency and d the direction [12].
As the wind speed increases, so do the wind drift,
the Stokes drift as well as surface currents. Because
all of them depend on the bathymetry and the coastal
geography, a comparison cannot be made on what
effects these have on the spills. If the spill occurs in
the open, with a deepness of more than 200 meters
(m), then the Stokes will be 10 to 20 % of the wind
one, as all of them (the drifts) will move in the same
direction.
3 Oil Weathering Mathematical
Analysis
Weathering is described as the process of spreading,
evaporation, emulsification, dissolution, dispersion
etc. of hydrocarbons mixed in water. All the above
processes will occur at the same time.
3.1 Spreading
The mechanical forces (gravity, inertia, viscous, and
interfacial tension and turbulent diffusion) cause the
horizontal expansion oil slick, this phenomenon is
defined as spreading. Oil expands in an arrangement
of a thin, constant layer with round mode, due to the
forces of gravity and surface tension. Spreading
coefficient is also known as surface tension,
according to Petroleum Engineers Guide to Oil Field
Chemicals and Fluids (2nd Edition), and the
Hydraulic Fracturing Chemicals and Fluids
Technology (2nd Edition). The spreading coefficient
is described as the divergence of the surface tension
foaming medium σf, the surface tension de-foamer σd
and the interfacial tension σdf [26].
f d df
S
(7)
The most commonly used equations/models for
spreading were developed by Fay (in three phases).
The second phase was adjusted by Wang et at.
13
2
2 0.5
20.5
0.98
ww
gV
At




(8)
Where A2 is the area in m2, g is the gravity in ms-
1, V is the volume in m3, t is the time in h, ρw is sea
water density 997kgm-3, υw is the kinematic
viscosity 0.0001 m2s-1.
Gravity is acting on the thick part of the slick,
which is layered on top of water, and a more heave
fluid is taken into consideration for spreading. Fay
was the first to introduce the theory of “gravitational
spreading against viscous resistance”, which states
that for a small amount of time when the spill is still
“young”, the impulse of the spill to expand is
opposed by inertia, while the primary force resisting
any spreading under gravity is the viscosity of the oil.
1 3 4 3
2
s
ss
tn
tk tK tK
tk
VC T dt
T

(9)
The equation implements the modification in the
area of the thick slick at any time interval, and Fay’s
suggestion, mentioned above, where C2(s) is a
constant, while the flow, flows from thick to thin
ΔVtn(s). The surface thickness of the thick part of the
surface oil slick volume is Ttk. The area of the thick
part of the volume is Atk, while dt is the time step
[2], [18].
ss
tn tn tn
VT
(10)
The increase in the area of the area of the thin
slick, is ΔAtn(s).
Spreading lasts for either a time frame of 48 hours
after each sub spill happens, or until the thickness of
the thin and thick slicks are equal. After the 48 hour
period passes then wind currents etc. (advection
forces) dominate the movement of the slick. The
increase in the area of the thin slick ΔΑtn(s) is
calculated using an equation similar to Fay’s (1971),
equivalent to the third root of area times the timestep
and the exponential function of the thickness.[2]
When the slick becomes very thin it stops spreading,
this is expressed by the last exponential:
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13 3
1exp 0.00001
s
ss
tn tn tk
C
C dt T

 

(11)
Where the model parameters are C1 and C3, the
thickness of the thick part of the surface slick is Ttk
and dt is the timestep.
Proposed by Lehr et al. was a stretched ellipse
along the path of the wind model, to resolve the
attended non-symmetrical expanding of slicks [19]:
1/3 1/3 1/4
3/4
4/3
1.13 /
0.0034
o
w o o
Q
R Q W
Vt
t




(12)
Where the length of the major and minor axis is R
and Q respectively. 20]
While Lehr et al. composed an altered Fay
spreading equation considering wind:
2/3 1/3
2/3 1/2 1/3 4/3
2270 40 wind
A V t V U t





(13)
Quoting Lehr et al.: “where A is the area of the oil
slick (m2); _ρ=ρw_ρo; V is the total volume of the
spilled oil in barrels; Uwind is the wind speed in
knots; and t is the time in minutes” [21].
4 Fate Weathering Visualization of
Spreading
Τhe issue of simulating and visualizing the spread of
an oil slick based on the introduced equations was
characterized and treated as a time series data and
analysis problem. The data points, thus the radius and
spreading of the oil spill were monitored and
visualized to indicate the spatial coverage of detected
oil spill over time in different experiments. Thus,
machine learning and time series data exploratory
analysis approaches, such as time-based indexing and
multi-step forecasting, were utilized to depict the
expansion of an oil spill through the time and based
on the various iterations that were conducted. The
latter can also be utilized to forecast the time-and-
space-varying velocity of an oil spill. In this context,
the visualization was based on laboratory
experiments of an oil slick spread and was
implemented tasks with the Python programming
language and the utilization of Anaconda
environment and IPython Notebook. Moreover,
several tools and libraries of the Python language for
the implementation of the abovementioned tasks were
utilized. For instance, the matplotlibpackage was
used to provide the final visualizations and plots for
the demonstration of the experimental results [24].
Additionally, numpywas utilized to perform quick
computations and mathematical equations, while the
capabilities of the pandas package and its data
structures and data frames were leveraged for
working with time series data, as the examined data
were characterized.
Furthermore, each record of the initial experiments
acts as a different time series. Hence, dA is used as
the step of the overall spill progress across time.
Starting from the initial spill with radius A in time
t=0 and reaching to A2 that is the final condition of
oil spill after t.
The utilization of the developed Python code on the
simulations resulted in interesting plots that showcase
the overall spreading of an oil spill through the
various simulations and initial number of drops. More
specifically, “Fig. 1” depicts a comparison between
the spreading rate of the three examined simulations
based on the initial drops of oils. The visual analysis
of this figure indicates that there is a tremendous
growth of the spread of the oil spill between an initial
1-Drop of oil and initial 5-Drops of oil. While, on the
other hand there is a small difference between the
spreading rates of 5-Drops as compared to initial 10-
Drops of oil. Moreover, it showcases that the 5-Drop
and 10-Drop simulations have almost the same high
exponential growth in the radius of the oil spill across
time. In contrary to the 1-Drop simulation where the
growth of the radius of the oil spill follows a more
linear increase.
Fig. 1: Comparison between the spreading of an oil
spill in the different experiments
What is more, Figure 1 above illustrates the
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DOI: 10.37394/232013.2022.17.16
Nikolaos Kastrounis, George Manias,
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graphical representation of the results obtained from
the python model using the data from the laboratory
experiment, the graph shows the increase of the rate
of spread for one (1), five (5) and ten (10) droplets of
oil, 0.0228gr each against the time. As it is clear from
the illustration there is an exponential increase on the
rate of spread of the oil slick in relation to time with
the increase of the volume of oil being disposed.
Trying to provide a more depth analysis on this
expansion and increasing rate of spreading between
the three different simulations “Fig. 2”. The latter
showcases the overall expansion in the covered area
of an oil spill over time. In all three subplots that are
presented in this figure the overall time for reaching
to the final condition (A2) is the same (t=3.0sec).
From this figure it is easily understood that in the
simulations of the 5-Drop and 10-Drop there is a
great expansion in the final area that the oil spill
covers as in comparison with the 1-Drop simulation.
Fig. 2: Comparison between the rates of spreading
between the three different simulations
The figure above, i.e, Fig. 2, illustrates the
spreading affect of the oil spill using python in
relation to the time. The x and y axis represent the
dimensions of the laboratory tank used to replicate
the spreading of the oil spill in centimeters (cm).
While the different oil spill spreading variations over
time are represented by the different color cycles as
depicted in the time scale on the right bottom of the
figure. In this respect, Fig. 2 provides a visual
representation of the spreading weathering effect that
occurs during an oil spill from the moment the
droplet reaches the water surface until the spreading
stops.
5 Discussion - Response System
Python simulations have been carried out based on
results and data obtained from the laboratory
experiments. The results of the python model
representations as well as of the laboratory
experiment oil spill feature a close resemblance. At
this point, it should be noted that both the laboratory
and the python model did not take into account the
other weathering processes mentioned in table 1,
apart from the spreading effect nor did the
accumulate for wind or water wave effects.
Trustworthy real-time data is required regarding
the movement and growth of the oil slick for the
response department. Nowadays this information is
provided by atmospheric and forecasting services like
NCEP and NOAA respectively. The most important
aspect in the response system is to identify the
location in order to forecast the movement of the oil
spill. The location as mentioned above plays the most
critical role because in order to tackle the oil spill and
create a response system there is first a need to create
a trajectory map. This map potentially will show any
boundaries (i.e., beaches) that might alter the
direction trajectory of the spill or even cause
beaching of the oil. It will also help decide which
type of response system will be used to clean or
control the oil spill.
There is a clear necessity for establishing a live-
action event response system to counter the negative
aftereffects of oil spill incidents on the environment
and society. This statement is greatly justified by the
fact that in recent years 30% and 25% of the yearly
spills occur with an average spillage of 160.000 and
290.000 tons from platforms and tankers respectively.
6 Conclusion Improvements Needed
The oil slick is depicted as a stream of individual
molecules for the analytical formulation. Each
individual molecule is depicting a body of oil
exposed to weathering and drift due to oceanic
conditions/forces acting on the slick. Relying upon
the ocean circumstances the depicting of the
molecules and the analytical formulation of the
weathering models change. These circumstances that
play a critical role include factors such as wind
currents etc. State of the art oil forecast models use
extrinsic data for currents, stokes drift, air water
temperature etc. Some elements of the ocean models
are replicated better than others, thus it is important
to know which the prevailing factor is in order to
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DOI: 10.37394/232013.2022.17.16
Nikolaos Kastrounis, George Manias,
Michael Filippakis, Dimosthenis Kyriazis
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Volume 17, 2022
choose the appropriate oil spill model.
The spill augur is done using a mathematical model
of the weathering. Weathering involves evaporation
dispersion emulsification, oil properties, chemical
properties, environmental conditions etc. Most
models typically do not take into account dissolution
and degradation. But these two factors are vital in
order to approximate the effect of the spill on the
environment and society. Oil has the ability to
dissolve from the surface of the slick in the column or
disperse. According to Mackay (1977), dissolution is
deliberated as a mass flux connected to solubrity and
temperature. Degradation depends on the chemical
properties of the oil of the spill, but there is a limited
amount of models that take into account
biodegradation. Taking into account the above
statements there is a clear need for the oil spill
modelling to make a distinction based on their
physical, chemical and toxicological characteristics
and trail their movement individually so that a higher
accuracy is achieved. Thus, it is crucial in order to
forecast the effect on the environment, to consider the
fate in the water column.
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