Figure 1.
Aurelia aurita bell geometries.
Aurelia aurita half bell profile in the (A) relaxed, (B) contracting and (C) contracted position. These images of A. aurita were taken during a flow characterization test using fluorescent dye. This test was conducted in ocean waters and the dye is seen as bright green in the images.
Figure 2.
BISMAC actuators and Robojelly.
Layout of BISMAC actuators with flaps having (A) rectangular, (B) tapered and (V) curved and tapered cross-section. Robojelly with (D) no flap (0% flap) and (E) Bio flap.
Figure 3.
(A) Robojelly with 200% flap setup on a mount in the water tank. The laser sheet is pointed at the bell. (B) Schematic of the TRDPIV test setup.
Figure 4.
Aurelia aurita bell kinematics.
(A) Aurelia aurita bell kinematics showing the exumbrella profiles over a full swimming cycle. The exumbrella profiles shown were selected arbitrarily for clarity. The margin trajectories are also shown for each side of the exumbrella profile. (B) Bell trajectories at selected points along the exumbrella arclength over a full swim cycle. The different percentages correspond to exumbrella arclengths from the apex to the margin. The 83% point corresponds to the flexion point and the 100% to the bell margin.
Figure 5.
(A) Curvature as a function of exumbrella arclength from apex to margin for exumbrella profiles in different stages. The profiles shown cover the four main states of the bell kinematics: relaxed, contracting, contracted and relaxing. The curvature is normalized by exumbrella arclength in the relaxed state. (B) Average normalized curvature as a function of exumbrella arclength from apex to margin. The curvature is averaged over a full cycle which includes the left and right profiles of the Aurelia aurita. The curvature is normalized by exumbrella arclength in the relaxed state. The flexion point was found to be located at an arclength of 83% from the apex.
Figure 6.
BISMAC actuator profile deformation with (A) constant, (B) tapered and (C) curved and tapered cross-section. Margin trajectories are shown with arrowheads indicating time progression. Profiles were down sampled in this figure for clarity.
Figure 7.
Superimposed exumbrella profile with flexion point location during contracting for the (A) Aurelia aurita and (B) Robojelly. The Robojelly inflexion point in (B) is for the single contraction profile shown.
Figure 8.
Robojelly swimming performance.
y-Position as a function of time for Robojelly with and without the bio flap during vertical swimming. The initial sinking state of the robot is shown along with the swimming state. The robot was not actuated during the initial sinking state.
Figure 9.
(A) Robojelly margin trajectories for different flap configurations. The trajectories are for a Robojelly normalized at its apex (position (0, 0)). Arrows indicate margin direction. (B) Bell margin displacement as a funciton of time during actuation for the different flap lengths. Displacments are shown from the beginning of actuation till the end of motion in the negative x-direction.
Figure 10.
Vorticity field of the Robojelly with bio flap at 0.2
Figure 11.
Dimensional and non-dimensional circulation.
(A) Robojelly circulation as a function of time for different flap configurations. (B) Non-dimensional circulation as a function of time scaled by orifice diameter.
Figure 12.
Non-dimensional Robojelly circulation using arclength.
Non-dimensional circulation scaled by bell arclength form apex to bell margin, as a function of non-dimensional time for different flap configurations.
Figure 13.
Non-dimensional circulation results.
(A) Non-dimensional circulation of the first peak as a function of flap length for β = 15. This does not include the bio flap. The normalize standard deviation is 0.23. (B) Normalized standard deviation of first peak circulation as a function of β.