When fluid flows past wall protrusions,periodic shedding of vortices occurs behind the protrusions,resulting in a complex flow field within the vortices.As these vortices continue to flow past a swimming biomimetic fish,the hydrodynamic coefficients of the fish undergo significant changes.Based on the multiple direct forcing immersed boundary method,combined with the Dirac function,the non-dimensional Navier-Stokes(N-S)equations for incompressible flow are solved to numerically simulate the swimming process of the biomimetic fish at low Reynolds numbers.To verify the accuracy of the algorithm and the self-developed program,validation calculations were performed for the flow around a cylinder and the swimming flow field of a NACA0012 shaped fish body.The calculated results agree well with the literature,confirming the effectiveness of the algorithm and the program.On this basis,the study investigates the influence of semi-circular wall protrusions on the hydrodynamic coefficients of the biomimetic fish swimming.The results show that when the biomimetic fish is close to the wall(d=0.25L),it experiences a lateral force away from the wall and a clockwise moment.When the biomimetic fish is farther from the wall(d=1.25L),it experiences a lateral force towards the wall and a counterclockwise moment.Overall,the wall protrusions make it easier for the biomimetic fish to swim within a certain height range from the wall,the wall protrusions also provide some drag reduction for the biomimetic fish swimming.
biomimetic fish swimmingnear-wall effectimmersed boundary methodnumerical simulation
维普
万方数据
