Zeszyty Naukowe 32(104) z. 2 105

Scientific Journals Zeszyty Naukowe Maritime University of Szczecin Akademia Morska w Szczecinie

2012, 32(104) z. 2 pp. 105–109 2012, 32(104) z. 2 s. 105–109

Testing of a oil spill mathematical model contained in PISCES II simulator

Kinga Łazuga

Maritime University of Szczecin, Faculty of Navigation, Institute of Marine Traffic Engineering 70-500 Szczecin, ul. Wały Chrobrego 1–2, e-mail: k.lazuga@am.szczecin.pl

Key words: SAR, wind, current, oil

Abstract PISCES II is a simulator designed to conduct research and training related to the rescue operation in the event

of an oil spill on any of the world region. The program includes a built-in mathematical model, enables the oil

spill of crude oil to observe the interaction in user-specified external conditions. This paper presents the

results of the analysis of mathematical model simulation Pisces II, the behavior of the oil slick in selected

hydrometeorological conditions.

PISCES II – oil spill simulator

Simulator PISCES II is designed to prepare and

conduct rescue action in the case of an oil spill. The

program dive into a comprehensive environmental

information, based on mathematical modeling

of oil spill and its interaction with geographical

restrictions, environmental phenomena, and the

spillage fighting.

Simulator PISCES II is used to predict the

behavior of the oil spill spreading on sea surface,

observing the processes taking place during the

interaction beetween oil, sea water and air. Also

simulator is used to coordinate rescue operations in

the case of oil spill and training.

Oil and processes occurring during the oil spill

Crude oil is a substance heterogeneous in terms

of both, physical and chemical properities. It is

a mixture of many hydrocarbons and sulfur

Fig. 1. The processes following the oil spill [1]

Kinga Łazuga

106 Scientific Journals 32(104) z. 2

compounds, oxygen and nitrogen. Due to the diver-

sity of chemical composition of different types of

oil, forecasting the behavior of this substance on

contact centers, such as water and air, is difficult.

Behaviour of oil and its products at the time of fill-

ing is determined by physical and chemical proper-

ties of spilled substance and external conditions that

accompany this spills.

Oil can also undergo a process such as evapora-

tion, emulsification, dissolution, microbial degrada-

tion, which may alter the physical properties of

spilled substance (Fig. 1).

Influance of hydrometeorological conditions on the simulation results

To see the properties of the simulator PISCES II

model, two points (one point on the Atlantic Ocean

and one point in the North Sea) were taken to simu-

lations.

In the case study of the impact of wind on the

processes taking place in oil slick 100 tons of IFO

300 were used (in form of slick on the surface of

the initial 0.1 km2 and a maximum initial thickness

3.3 mm). In each simulation the wind direction was

north, and its speed was 5–30 m/s.

In the current case study of the impact of surface

processes occurring in the stain 50 and 100 tons of

IFO 300 belongs to a group of medium-sized ma-

rine fuels were used.

All simulations were carried out for total annihi-

lation of spilled material from the surface of water

or until the simulation duration exceeded 100

hours.

Fig. 2. Properties of fuel oil IFO 300

Wind effect

One of the main factors influencing the move-

ment of the oil slick is the wind force, which main-

ly affects the speed of some physical processes

occurring in the oil slick. In the following simula-

tions the winds of 5, 10, 15, 20, 25 and 30 m/s and

wind direction Kw = 000° were taken into account.

Simulations results are presented in next subsec-

tions.

The impact of wind speed for the duration of the

simulation

Wind force has mainly affected the speed of

movement of oil slick on the surface. The figure

below shows the dependence of the duration of the

simulation on wind speed.

Fig. 3. The duration of the simulation depending on wind speed

Effect of wind speed on evaporation

Evaporation spill (volatilization light fractions

of oil) is very intense. Within one to three weeks of

the uprising even shed about 1/3 of the spilled oil

can evaporate. Oxidation takes place most inten-

sively in the first hours after the oil spillage.

With increasing of wind force and air tempera-

ture evaporation is increasing too. Evaporation of

the fraction of light causes an increase in density

and viscosity of spilled oil. Evaporation process,

depending on wind speeds present figures 4 and 5.

Fig. 4. Evaporation of oil during the simulation for wind speeds

of 5 m/s

393.00 150.00

26.53

7.80 3.23 1.67

0

10

20

30

40

50

60

70

80

90

100

5 10 15 20 25 30

Du

rati

on

of

sim

ula

tio

n [

h]

Wind speed [m/s]

Ts [h]

0

2

4

6

8

10

12

14

16

18

20

"0:0

0"

"19

:00

" "3

8:0

0"

"57

:00

" "7

6:0

0"

"95

:00

" "1

14

:00

" "1

33

:00

" "1

52

:00

" "1

71

:00

" "1

90

:00

" "2

09

:00

" "2

28

:00

" "2

47

:00

" "2

66

:00

" "2

85

:00

" "3

04

:00

" "3

23

:00

" "3

42

:00

" "3

61

:00

" "3

80

:00

"

Evap

ora

tio

n [

t]

Vw=5 m/s

Testing of a oil spill mathematical model contained in PISCES II simulator

Zeszyty Naukowe 32(104) z. 2 107

Fig. 5. Evaporation of oil during the simulation for wind speeds

of 10–30 m/s

Effect of wind speed on the dispersion

Under certain conditions, oil can be dispersed

(the formation of a suspension of microparticles of

oil in water) by mechanical activity of the sea.

The size of dispersion is a function of sea state and

oil properties. Dispersion begins shortly after oil

spillage.

In view of the fact that the sea state is closely

dependent on the wind force dispersion acting most

rapidly with high wind speed [1]. Dispersion

process depending on wind speed present figures 6

and 7.

Speed processes in the oil stain, depending on the

wind

Figure 8 shows the processes taking place after

the oil spill on the water surface at 15°C, air tem-

perature 20°C and wind speed 15 m/s.

Current Impact

Another of the main factors influencing the

behavior of the oil slick in water is a surface cur-

rent, or tidal current. Current parameters affect

mainly the direction and speed of movement of oil

slick.

Influence of surface current on the processes occur-

ring in the spot crude oil

If on the oil slick has influance only a surface

current (in this case 10 m/s) and wind speed is 0

m/s, the only process resulting from the action of

this current is the movement of oil slick according

to the current direction (Fig. 9). Changing the direc-

tion of current is caused by coastline shape.

Fig. 6. Dispersion of crude oil at wind speeds of 5 m/s

Fig. 7. Dispersion of oil in the wind speeds of 10–30 m/s

Fig. 8. Processes occurring after oil spillage at a wind speed of

15 m/s

7.4

4.9

2.4

1.3

0.7

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0

1

2

3

4

5

6

7

8

"0:0

0"

"3:0

0"

"6:0

0"

"9:0

0"

"12

:00

"

"15

:00

"

"18

:00

"

"21

:00

"

"24

:00

"

"27

:00

"

"30

:00

"

"33

:00

"

"36

:00

"

"39

:00

"

"42

:00

"

Evap

ora

tio

n [

t]

Evap

ora

tio

n [

t]

Vw=10 m/s Vw=15 m/s

Vw=20 m/s Vw=25 m/s

Vw=30 m/s

0

5

10

15

20

25

30

"0:0

0"

"19

:00

"

"38

:00

"

"57

:00

"

"76

:00

"

"95

:00

"

"11

4:0

0"

"13

3:0

0"

"15

2:0

0"

"17

1:0

0"

"19

0:0

0"

"20

9:0

0"

"22

8:0

0"

"24

7:0

0"

"26

6:0

0"

"28

5:0

0"

"30

4:0

0"

"32

3:0

0"

"34

2:0

0"

"36

1:0

0"

"38

0:0

0"

Dis

per

sio

n [

t] Vw=5 m/s

0

20

40

60

80

100

120

"0:0

0"

"3:0

0"

"6:0

0"

"9:0

0"

"12

:00

"

"15

:00

"

"18

:00

"

"21

:00

"

"24

:00

"

"27

:00

"

"30

:00

"

"33

:00

"

"36

:00

"

"39

:00

"

"42

:00

"

Dis

per

sio

n [t

]

Vw=10 m/s Vw=15 m/s

Vw=20 m/s Vw=25 m/s

Vw=30 m/s

0

20

40

60

80

100

120

1 5 9 13 17 21 25

Am

ou

nt

[t]

Floating amount [t]

Evaporated amount [t]

Dispersed amount [t]

Kinga Łazuga

108 Scientific Journals 32(104) z. 2

Impact of current and wind on the behavior of the oil

slick

When on the oil slick in the same time acting

current and wind, movement of this oil slick is

mainly determined by the current parameters. Wind

direction has little effect (3%) to the direction

of movement of oil slick, while the wind speed

determines the speed of most physical processes

occurring in the oil slick.

Fig. 9. The movement of oil slicks at the current speed of 10 m/s

Fig. 10. The direction of movement of oil slick under influence on current (Vc = 10 m/s) and wind (Vw = 10 m/s)

Testing of a oil spill mathematical model contained in PISCES II simulator

Zeszyty Naukowe 32(104) z. 2 109

The intensity of evaporation of light petroleum

fractions is dependent on air temperature and wind

force. In the case described below the simulation

temperature was 20°C and the water temperature

was 15°C.

Fig. 11. Processes occurring in the oil slick when exposed to

current and wind

Conclusions

Reported results relate only to simulations of the

physical processes occurring after spillage of IFO

300 oil on the sea surface. Simulations show that

the movement of the slick is mainly influence by

the direction and speed of current. On physical

processes such as evaporation, dispersion, or sink-

ing, the greatest impact has the force of the wind.

It is difficult to determine how fast these processes

will occur after the spillage, because they are

affected by other factors such as air and water

temperature and density of the water. Therefore,

this research will continue.

References

1. The national plan to combat hazards and pollution of the

marine environment. Maritime Search and Rescue, Gdynia

2005.

2. PISCES II User Manual. Transas Ltd., 2008.

3. Specyfication for PISCES II. Transas Ltd., 2007.

0

10

20

30

40

50

60

70

80

90

100

Am

ou

nt

[t]

Floating amount [t]

Evaporated amount [t]

Dispersed amount [t]