Hydrodynamics of linear acceleration in bluegill sunfishLepomis macrochirus

Abstract

STATEMENT1 Bluegill sunfish accelerate primarily by increasing the total amount of force produced in each tail 2 beat but not by substantially redirecting forces. 3ABSTRACT 4 In their natural habitat, fish rarely swim steadily. Instead they frequently 5 accelerate and decelerate. Relatively little is known about how fish produce extra force 6 for acceleration in routine swimming behavior. In this study, we examined the flow 7 around bluegill sunfish Lepomis macrochirus during steady swimming and during 8 forward acceleration, starting at a range of initial swimming speeds. We found that 9 bluegill produce vortices with higher circulation during acceleration, indicating a higher 10 force per tail beat, but do not substantially redirect the force. We quantified the flow 11 patterns using high speed video and particle image velocimetry and measured 12 acceleration with small inertial measurement units attached to each fish. Even in steady 13 tail beats, the fish accelerates slightly during each tail beat, and the magnitude of the 14 acceleration varies. In steady tail beats, however, a high acceleration is followed by a 15 lower acceleration or a deceleration, so that the swimming speed is maintained; in 16 unsteady tail beats, the fish maintains the acceleration over several tailbeats, so that the 17 swimming speed increases. We can thus compare the wake and kinematics during 18 single steady and unsteady tailbeats that have the same peak acceleration. During 19 unsteady tailbeats when the fish accelerates forward for several tailbeats, the wake 20 vortex forces are much higher than those at the same acceleration during single 21 tailbeats in steady swimming. The fish also undulates its body at higher amplitude and 22 frequency during unsteady tailbeats. These kinematic changes likely increase the fluid 23 dynamic added mass of the body, increasing the forces required to sustain acceleration 24 over several tailbeats. The high amplitude and high frequency movements are also 25 likely required to generate the higher forces needed for acceleration. Thus, it appears 26 that bluegill sunfish face a tradeoff during acceleration: the body movements required 27 for acceleration also make it harder to accelerate. 28

The fish body functions as an airfoil: surface pressures generate thrust during carangiform locomotion

“…All values were on the same order of magnitude as previous estimates from wake analyses (39,40). Trout produce positive pressure thrust more anteriorly than bluegill…”

“…Presumably, timing, magnitude, and location of forces, in addition to the relative role of positive and negative pressure, could all change during accelerations. For example, many carangiform swimmers, including bluegill, have larger head and tail oscillation amplitudes and larger tailbeat frequencies during accelerations (39,47), leading to larger added masses and larger total forces (39). Interestingly, in bluegill (39) but not trout (47), these increases occur without substantially redirecting the net thrust forces relative to steady swimming, suggesting that there are differences in the force production mechanics among species and across behaviors like steady swimming and accelerations.…”

Emergence of a giant rotating cluster of fish in three dimensions by local interactions

“…The sustained speed v 0 is the swimming speed that can last almost indefinitely, and is 1 ∼ 2 BL s −1 [47][48][49][50]. The acceleration is on the order of 0.1 ∼ 1 BL s −2 both when the fish is perturbed by flow [51,52], and when it is interacting with other fish in the radius r e [14]. We thus adopt τ 0 = 1 sec as the time constant.…”

Boric Acid (H3(BO3): Recognize The Molecular Interactions in Solutions

“…(60) Dimana, ia menjaga kesetimbangan dengan basa konjugasinya (61-63) (konsentrasi ion borat 50-100 ppm setara dengan boron). Berdasarkan penelitian ternyata asam borat juga dapat digunakan pada pembangkit listrik tenaga nuklir (220)(221)(222) sebagai racun neutron. (64) Pembangkit listrik tenaga nuklir (65)(66)(67)(68) tidak menyumbang emisi karbon (69)(70)(71) sehingga tidak menyebabkan global warming (72)(73)(74)(75) seperti pembangkit listrik kebanyakan.…”

“…(2) Kation (108; 184; 194-196) bereaksi dengan percepatan menuju elektroda (197) negatif dan anion (108; 159; 194; 198; 199) bereaksi dengan percepatan menuju elektroda positif. Akan tetapi,saat ion bergerak melalui pelarut (200)(201)(202) maka ion akan mengalami gaya gesekan (203)(204)(205)(206)(207) memperlambat muatan (208) yang setara dengan kecepatannya.dan jika dianalogikan hukumStokes (209)(210)(211)(212)(213) untuk bola radius (190; 214-217) a dan s berlaku pada skala mikroskopis,maka kita dapat menuliskan gaya perlambatan (218)(219)(220)(221)(222) ini dibawah ini:…”