Bioinspired jet propulsion through periodic jetting and refilling is a promising method to achieve high swimming speed with relatively low body stiffness. By using a fluid-structure interaction model, we demonstrate that it is possible to increase the efficiency of this locomotion mode by using a valve-controlled auxiliary inlet. The inlet is closed during the jetting phase yet opened during the refilling phase. Its primary function is to reduce the speed of the ingoing flow so that it takes much less energy to refill and the corresponding energy waste is mitigated. Our results show that a properly designed auxiliary inlet greatly reduces the cost of transport with very little sacrifice in swimming speed. For example, in a typical case the inclusion of such an inlet reduces the cost of transport by 60%, yet the decrease in forward speed is only 2.3%.

• Received 7 November 2022
• Accepted 27 March 2023

DOI:https://doi.org/10.1103/PhysRevFluids.8.043101