At the millimeter scale and in the intermediate Reynolds number (Re) regime, the midge and mosquito larvae can reach swimming speeds of more than one body length per cycle performing a “figure eight” gait, in which their elongated bodies periodically bend nearly into circles and then fully unfold. To elucidate the propulsion mechanism of this cycle of motion, we conducted a three-dimensional (3D) numerical study, which investigates the hydrodynamics of undergoing the prescribed kinematics. We found novel propulsion mechanisms, such as modulating the body deformation rate to dynamically increase the maximum net propulsion force, using asymmetric kinematics to generate torque and the appropriate rotation, and controlling the radius of the curled body to manipulate the moment of inertia. The figure eight gait is found to achieve propulsion at a wide range of Re but is most effective at intermediate Re. The results were further validated experimentally, via the development of a soft millimeter-sized robot that can reach comparable speeds using the figure eight gait.

1.
A. E.
Hosoi
and
E.
Lauga
, “
Mechanical aspects of biological locomotion
,”
Exp. Mech.
50
,
1259
1261
(
2010
).
2.
E.
Lauga
, “
Bacterial hydrodynamics
,”
Annu. Rev. Fluid Mech.
48
,
105
130
(
2016
).
3.
J.
Sznitman
,
X.
Shen
,
P. K.
Purohit
, and
P. E.
Arratia
, “
The effects of fluid viscosity on the kinematics and material properties of C. elegans swimming at low Reynolds number
,”
Exp. Mech.
50
,
1303
1311
(
2010
).
4.
M.
Sfakiotakis
,
D. M.
Lane
, and
J. B. C.
Davies
, “
Review of fish swimming modes for aquatic locomotion
,”
IEEE J. Oceanic Eng.
24
,
237
252
(
1999
).
5.
J.
Gray
, “
How fishes swim
,”
Sci. Am.
197
,
48
55
(
1957
).
6.
G. I.
Taylor
, “
Analysis of the swimming of long and narrow animals
,”
Proc. R. Soc. London Ser. A
214
,
158
183
(
1952
).
7.
E.
Lauga
and
T. R.
Powers
, “
The hydrodynamics of swimming microorganisms
,”
Rep. Prog. Phys.
72
,
096601
(
2009
).
8.
W. M.
Van Rees
,
M.
Gazzola
, and
P.
Koumoutsakos
, “
Optimal morphokinematics for undulatory swimmers at intermediate Reynolds numbers
,”
J. Fluid Mech.
775
,
178
188
(
2015
).
9.
T.
Dombrowski
and
D.
Klotsa
, “
Kinematics of a simple reciprocal model swimmer at intermediate Reynolds numbers
,”
Phys. Rev. Fluids
5
,
063103
(
2020
).
10.
N.
Cohen
and
J. H.
Boyle
, “
Swimming at low Reynolds number: A beginners guide to undulatory locomotion
,”
Contemp. Phys.
51
,
103
123
(
2010
).
11.
J. F.
van Weerden
,
D. A.
Reid
, and
C. K.
Hemelrijk
, “
A meta-analysis of steady undulatory swimming
,”
Fish Fish.
15
,
397
409
(
2014
).
12.
M.
Gazzola
,
M.
Argentina
, and
L.
Mahadevan
, “
Scaling macroscopic aquatic locomotion
,”
Nat. Phys.
10
,
758
761
(
2014
).
13.
M.
Triantafyllou
,
F.
Hover
,
A.
Techet
, and
D.
Yue
, “
Review of hydrodynamic scaling laws in aquatic locomotion and fishlike swimming
,”
Appl. Mech. Rev.
58
,
226
(
2005
).
14.
Y.-L.
Yu
and
K.-J.
Huang
, “
Scaling law of fish undulatory propulsion
,”
Phys. Fluids
33
,
061905
(
2021
).
15.
S.
Gupta
,
A.
Sharma
,
A.
Agrawal
,
M. C.
Thompson
, and
K.
Hourigan
, “
Hydrodynamics of a fish-like body undulation mechanism: Scaling laws and regimes for vortex wake modes
,”
Phys. Fluids
33
,
101904
(
2021
).
16.
D.
Zhang
,
G.
Pan
,
L.
Chao
, and
Y.
Zhang
, “
Effects of Reynolds number and thickness on an undulatory self-propelled foil
,”
Phys. Fluids
30
,
071902
(
2018
).
17.
F.
Karakas
,
A. E.
Maas
, and
D. W.
Murphy
, “
A novel cylindrical overlap-and-fling mechanism used by sea butterflies
,”
J. Exp. Biol.
223
,
jeb221499
(
2020
).
18.
Y.
Chang
and
J.
Yen
, “
Swimming in the intermediate Reynolds range: Kinematics of the Pteropod Limacina helicina
,”
Integr. Comp. Biol.
52
,
597
615
(
2012
).
19.
J.
Brackenbury
, “
Locomotory modes in the larva and pupa of Chironomus plumosus (Diptera, Chironomidae)
,”
J. Insect Physiol.
46
,
1517
1527
(
2000
).
20.
H. C.
Berg
and
R. A.
Anderson
, “
Bacteria swim by rotating their flagellar filaments
,”
Nature
245
,
380
382
(
1973
).
21.
Y.
Magariyama
,
S.
Sugiyama
, and
S.
Kudo
, “
Bacterial swimming speed and rotation rate of bundled flagella
,”
FEMS Microbiol. Lett.
199
,
125
129
(
2001
).
22.
K.
Ishimoto
,
J.
Cosson
, and
E. A.
Gaffney
, “
A simulation study of sperm motility hydrodynamics near fish eggs and spheres
,”
J. Theor. Biol.
389
,
187
197
(
2016
).
23.
F.-B.
Tian
and
L.
Wang
, “
Numerical modeling of sperm swimming
,”
Fluids
6
,
73
(
2021
).
24.
W.
Nachtigall
, “
Zur lokomotionsmechanik schwimmender dipterenlarven
,”
Z. Vgl. Physiol.
44
,
509
522
(
1961
).
25.
J.
Brackenbury
, “
The vortex wake of the free-swimming larva and pupa of CULEX PIPIENS (Diptera)
,”
J. Exp. Biol.
204
,
1855
1867
(
2001
).
26.
J.
Brackenbury
, “
Swimming kinematics and wake elements in a worm-like insect: The larva of the midge Chironomus plumosus (Diptera)
,”
J. Zool.
260
,
195
201
(
2003
).
27.
K.
Kikuchi
and
O.
Mochizuki
, “
Consideration of thrust in escaping motion of a mosquito larva
,”
J. Aero Aqua Bio-Mech.
1
,
111
116
(
2010
).
28.
C. S. X.
Ng
,
M. W. M.
Tan
,
C.
Xu
,
Z.
Yang
,
P. S.
Lee
, and
G. Z.
Lum
, “
Locomotion of miniature soft robots
,”
Adv. Mater.
33
,
2003558
(
2021
).
29.
S. O.
Demir
,
U.
Culha
,
A. C.
Karacakol
,
A.
Pena-Francesch
,
S.
Trimpe
, and
M.
Sitti
, “
Task space adaptation via the learning of gait controllers of magnetic soft millirobots
,”
Int. J. Rob. Res.
40
,
1331
1351
(
2021
).
30.
E. D.
Tytell
and
G. V.
Lauder
, “
The hydrodynamics of eel swimming—I: Wake structure
,”
J. Exp. Biol.
207
,
1825
1841
(
2004
).
31.
R.
Mittal
,
H.
Dong
,
M.
Bozkurttas
,
F.
Najjar
,
A.
Vargas
, and
A.
Von Loebbecke
, “
A versatile sharp interface immersed boundary method for incompressible flows with complex boundaries
,”
J. Comput. Phys.
227
,
4825
4852
(
2008
).
32.
H.
Luo
,
H.
Dai
,
P. J. F.
de Sousa
, and
B.
Yin
, “
On the numerical oscillation of the direct-forcing immersed-boundary method for moving boundaries
,”
Comput. Fluids
56
,
61
76
(
2012
).
33.
J.
Song
,
Y.
Zhong
,
H.
Luo
,
Y.
Ding
, and
R.
Du
, “
Hydrodynamics of larval fish quick turning: A computational study
,”
Proc. Inst. Mech. Eng., Part C
232
,
2515
2523
(
2018
).
34.
G.
Liu
,
Y.
Ren
,
H.
Dong
,
O.
Akanyeti
,
J. C.
Liao
, and
G. V.
Lauder
, “
Computational analysis of vortex dynamics and performance enhancement due to body–fin and fin–fin interactions in fish-like locomotion
,”
J. Fluid Mech.
829
,
65
88
(
2017
).
35.
J.
Li
,
X.
Luo
, and
Z.
Kuang
, “
A nonlinear anisotropic model for porcine aortic heart valves
,”
J. Biomech.
34
,
1279
1289
(
2001
).
36.
T.
Ming
and
Y.
Ding
, “
Transition and formation of the torque pattern of undulatory locomotion in resistive force dominated media
,”
Bioinspiration Biomimetics
13
,
046001
(
2018
).
37.
J.
Jiang
,
L.
Yang
, and
L.
Zhang
, “
Closed-loop control of a helmholtz coil system for accurate actuation of magnetic microrobot swarms
,”
IEEE Rob. Autom. Lett.
6
,
827
834
(
2021
).
38.
J.
Brackenbury
, “
Escape manoeuvres in damsel-fly larvae: Kinematics and dynamics
,”
J. Exp. Biol.
206
,
389
397
(
2003
).
39.
V.
Di Santo
,
E.
Goerig
,
D. K.
Wainwright
,
O.
Akanyeti
,
J. C.
Liao
,
T.
Castro-Santos
, and
G. V.
Lauder
, “
Convergence of undulatory swimming kinematics across a diversity of fishes
,”
Proc. Natl. Acad. Sci.
118
,
e2113206118
(
2021
).
40.
M. J.
Lighthill
, “
Large-amplitude elongated-body theory of fish locomotion
,”
Proc. R. Soc. London Ser. B
179
,
125
138
(
1971
).
41.
A. D.
Huryn
, “
Growth and voltinism of lotic midge larvae: Patterns across an Appalachian Mountain basin
,”
Limnol. Oceanogr.
35
,
339
351
(
1990
).
42.
M.
Zeller
and
J. C.
Koella
, “
Effects of food variability on growth and reproduction of Aedes aegypti
,”
Ecol. Evol.
6
,
552
559
(
2016
).
43.
J. L.
van Leeuwen
,
C. J.
Voesenek
, and
U. K.
Müller
, “
How body torque and Strouhal number change with swimming speed and developmental stage in larval zebrafish
,”
J. R. Soc. Interface
12
(
110
),
20150479
(
2015
).
44.
L.
Fuiman
and
R.
Batty
, “
What a drag it is getting cold: Partitioning the physical and physiological effects of temperature on fish swimming
,”
J. Exp. Biol.
200
,
1745
1755
(
1997
).
45.
N.
Xia
,
B.
Jin
,
D.
Jin
,
Z.
Yang
,
C.
Pan
,
Q.
Wang
,
F.
Ji
,
V.
Iacovacci
,
C.
Majidi
,
Y.
Ding
, and
L.
Zhang
, “
Decoupling and reprogramming the wiggling motion of midge larvae using a soft robotic platform
,”
Adv. Mater.
34
,
e2109126
(
2022
).
46.
P.
Domenici
and
R.
Blake
, “
The kinematics and performance of fish fast-start swimming
,”
J. Exp. Biol.
200
,
1165
1178
(
1997
).
47.
D.
Weihs
, “
The mechanism of rapid starting of slender fish
,”
Biorheology
10
,
343
350
(
1973
).
48.
F.
Xie
,
Z.
Li
,
Y.
Ding
,
Y.
Zhong
, and
R.
Du
, “
An experimental study on the fish body flapping patterns by using a biomimetic robot fish
,”
IEEE Rob. Autom. Lett.
5
,
64
71
(
2020
).
49.
M.
Burrows
and
M.
Dorosenko
, “
Rapid swimming and escape movements in the aquatic larvae and pupae of the phantom midge Chaoborus crystallinus
,”
J. Exp. Biol.
217
(
14
),
2468
2479
(
2014
).
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