This document summarizes a presentation given at the International Symposium on BioMathematics in 2015 in Bandung, Indonesia. The presentation models the motion of microorganisms using a granular model that represents cells as connected spherical particles subjected to oscillating spring and drag forces from the surrounding fluid. Simulation results show noticeable displacement occurs when the oscillation periods of the spring and drag forces are similar, while other conditions produce little average displacement over time. The model provides insight into how microorganism motion can arise from interactions between an organism's shape changes and fluid forces.
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Symomath 2015 Microorganism Motion Simulation
1. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
1
Simulation of Microorganism Motion
in Fluid Based on Granular Model
Sparisoma Viridi1
and Nuning Nuraini2
1
Physics Department, Institut Teknologi Bandung
2
Mathematics Department, Institut Teknologi Bandung
Jalan Ganesha 10, Bandung 40132, Indonesia
1
dudung@fi.itb.ac.id, 2
nuning@math.itb.ac.id
2. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
2
Outline
• Introduction
• Model
• Results
• Summary
3. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
3
Introduction
4. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
4
Motion patterns of microorganism
• The patterns are unique: (1) orientation, (2)
wobbling, (3) gyration, and (4) intensive
surface probing (Leal-Taixé et al., 2010)
L. Leal-Taixé, M. Heydt, S. Weiße, A. Rosenhahn, B. Rosenhahn, Pattern
Recognition 6376, 283-292 (2010).
5. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
5
An active fluid
• Turbulence flow can occur in high viscous fluid
or in low Reynolds number (Aranson, 2013)
I. Aranson, Physics 6, 61 (2013).
6. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
6
Flagella as thruster
• Flagella introduces force and torque to the
fluid (Yang et al., 2012)
C. Yang, C. Chen, Q. Ma, L. Wu, T. Song, Journal of Bionic Engineering 9,
200-210 (2012).
7. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
7
Shrink and swallow model
• Pressure difference can induce motion (Viridi
and Nuraini, 2014)
S. Viridi, N. Nuraini, AIP Conference Proceedings 1587, 123-126 (2014).
9. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
9
Two grain model
• Two spherical particles as cells, which are
connected by a spring
mi
mj
kij
10. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
10
Push and pull spring force
• Spring force
lij is normal length of the spring
kij is spring constant
rij is distance between mass mi and mj
( ) ijijijijij rlrkS ˆ−−=
11. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
11
Fluid drag force
• Drag force
Cd is drag constant
A is cross sectional area
ρf is fluid density
vf is fluid velocity
( )
fi
fi
dfi
vv
vv
CAD
−
−
−=
3
2
1
ρ
12. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
12
Change of spring normal length
• Spring normal length varies with time
Tbridge is oscillation period of bridge between
cells
( )L
T
t
Llij α
π
α −+
= 1
2
sin
bridge
13. Change of drag coefficient
• Both cell can have same or different Cd
i = 1, 2 for each particle
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
13
( ) ( )min,max,
drag
min,max,
2
12
cos
2
1
, ddddid CC
T
t
CCC +
−=
π
14. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
14
Molecular dynamics method
• Newton second law of motion
• Euler method
+= ∑j
ijii SD
m
a
1
( ) ( ) tatvttv iii ∆+=∆+
( ) ( ) ( ) ttvtrttr ii ∆+=∆+
15. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
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Results
16. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
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Displacement
17. Same drag constant
• Cd = 0.1, Cd = 0.1
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
17
18. Same drag constant (cont.)
• Cd = 0.1, Cd = 0.4
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
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19. Same drag constant (cont.)
• Cd = 0.4, Cd = 0.1
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
19
20. Same drag constant (cont.)
• Cd = 0.4, Cd = 0.4
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
20
21. Influence of frequency
• Tbridge = 2
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
21
22. Influence of frequency
• Tbridge = 2.5
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
22
23. Oscillating drag constant
• Tbridge = 1, Tdrag = 0.5
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
23
24. Oscillating drag constant (cont.)
• Tbridge = 1, Tdrag = 1
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
24
25. Oscillating drag constant (cont.)
• Tbridge = 1, Tdrag = 1.5
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
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26. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
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Summary
27. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
27
Summary
• Microorganism motion can be modeled by
oscillating spring normal length and drag
constant
• Noticeable displacement is observed if
Tspring ~ Tdrag
• Other than that condition gives zero displace-
ment in average for long observation time
28. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
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Acknowledgement
29. Acknowledgement
• This work is supported by Institut Teknologi
Bandung, and Ministry of Higher Education
and Research, Indonesia, through the scheme
Penelitian Unggulan Perguruan Tinggi – Riset
Desentralisasi Dikti with contract number
310i/I1.C01/PL/2015
The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
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30. The International Symposium on
BioMathematics (Symomath) 2015
4-6 November 2015,
Bandung, Indonesia
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Thank you