Auxiliary Material for
Wavelength Selection and Symmetry Breaking in Orbital Wave Ripples
Jaap Nienhuis (Massachusetts Institute of Technology, Cambridge, MA)
Taylor Perron (Massachusetts Institute of Technology, Cambridge, MA)
Justin Kao (Massachusetts Institute of Technology, Cambridge, MA)
Paul Myrow (Colorado College, Colorado Springs, CO)
Journal of Geophysical Research Earth Surface, 2014
The auxiliary material for this paper consists of 3 time-lapse videos and 3 animations. The timelapse videos (S1, S2 and S6) show wave tank experiments of ripple wavelength shortening,
wavelength lengthening and ripples growing from a bump. The 3 animations (S3, S4 and S5)
show Lattice Boltzmann Method model results of fast flow over small (S3), equilibrium (S4) and
large (S5) ripples. Captions and text in the paper refer to these specific movies individually.
S1: Time-lapse video of ripple shortening recorded in the wave tank. The view covers an area of
approximately 30 cm along flume by 60 cm across flume. Wave propagation is to the right. The
lower right corner shows the image time stamp. Wave period (T) is 1.28 s, wave height (H) is
7.5 cm and the orbital diameter (d) at the bed is 5 cm. The initial ripple wavelength () is 7 cm.
After 20 minutes, the ripple wavelength adjusted to its equilibrium value of 3.2 cm.
S2: Time-lapse video of ripple widening recorded in the wave tank. The view covers an area of
approximately 30 cm along flume by 60 cm across flume. Wave propagation is to the right. The
lower right corner shows the image time stamp. Wave period (T) is 2.8 s, wave height (H) is 5.8
cm and the orbital diameter (d) at the bed is 12 cm. The initial ripple wavelength () is 4 cm.
During 7 hours, the ripple wavelength slowly changed towards an equilibrium value of 7.8 cm.
The time-lapse is cropped to save bandwidth.
S3: Model simulation of flow over 8 ripples. Colors indicate velocity magnitude (ms-1). Black
markers are passive tracers. Wave period (T) is 3 s, the velocity amplitude (u0) is 0.08 ms-1 and
the orbital diameter (d) is 7.7 cm. Ripple wavelength () is 2.5 cm, /d < 0.65.
S4: Model simulation of flow over 4 ripples. Colors indicate velocity magnitude (ms-1). Black
markers are passive tracers. Wave period (T) is 3 s, the velocity amplitude (u0) is 0.08 ms-1 and
the orbital diameter (d) is 7.7 cm. Ripple wavelength () is 5 cm, /d = 0.65.
S5: Model simulation of flow over 2 ripples. Colors indicate velocity magnitude (ms-1). Black
markers are passive tracers. Wave period (T) is 3 s, the velocity amplitude (u0) is 0.08 ms-1 and
the orbital diameter (d) is 7.7 cm. Ripple wavelength () is 10 cm, /d > 0.65.
S6: Time-lapse video of ripple evolution from a single crest recorded in the wave tank. The view
covers an area of approximately 40 cm along flume by 60 cm across flume. Wave propagation is
to the right. The lower right corner shows the image time stamp. Wave period (T) is 2.8 s, wave
height (H) is 6 cm and the orbital diameter (d) at the bed is 13 cm. The initial crest height () is
4 cm. After 3.5 hours, a ripple field developed with a ripple wavelength of 8.5 cm.