To capture prey by suction, fish generate a flow of water that enters the mouth, and exits at the back of the head. It was previously hypothesized prey-capture performance is improved by a streamlined shape of the posterior region of the pharynx, which enables an unobstructed outflow with minimal hydrodynamic resistance. However, this hypothesis remained untested for several decades. Using computational fluid dynamics simulations, we now managed to quantify the effects of different shapes of the posterior pharynx on the dynamics of suction feeding, based on a feeding act of a sunfish (Lepomis gibbosus). In contrast to what was hypothesized, the effects of the imposed variation in shape were negligible: flow velocity patterns remained essentially identical, and the effects on feeding dynamics were negligibly small. This remarkable hydrodynamic insensitivity implies that, in course of the evolution, the observed wedge-like protrusions of the pectoral surfaces of the pharynx probably resulted from spatial constraints and/or mechanical demands on the musculoskeletal linkages, rather than constraints imposed by hydrodynamics. Our study therefore exceptionally shows that a streamlined biological shape subjected to fluid flows is not always the result of selection for hydrodynamic improvement.
CFD models b1 to b4
Ansys 19.0 Workbench project file that contains the model and data for the simulation described in the article as "model b1", "model b2", "model b3", "model b4". Individual data files from three time steps (8 ms, 20 ms, and 200 ms), and user-defined function input source files can be found under /dp0/FFF-17/Fluent, /dp0/FFF-22/Fluent, /dp0/FFF-23/Fluent, /dp0/FFF-24/Fluent. Zip file, 0.49 GB.
suction_model_PP&SVW2018_b1_b_b3_b4.zip
CFD model a1 PART1/7
Ansys 19.0 Workbench project file that contains the model and data for the simulation described in the article as "model a1".Individual data files from time steps, and user-defined function input source files can be found under /dp0/FFF-9/Fluent and /dp0/FFF-10/Fluent. Zip file, 6.36 GB.
suction_model_PP&SVW2018_a1.zip.001
CFD model a1 PART2/7
suction_model_PP&SVW2018_a1.zip.002
CFD model a1 PART3/7
suction_model_PP&SVW2018_a1.zip.003
CFD model a1 PART4/7
suction_model_PP&SVW2018_a1.zip.004
CFD model a1 PART5/7
suction_model_PP&SVW2018_a1.zip.005
CFD model a1 PART6/7
suction_model_PP&SVW2018_a1.zip.006
CFD model a1 PART7/7
suction_model_PP&SVW2018_a1.zip.007
CFD model a2 PART1/7
Ansys 19.0 Workbench project file that contains the model and data for the simulation described in the article as "model a2".Individual data files from time steps, and user-defined function input source files can be found under /dp0/FFF-14/Fluent and /dp0/FFF-15/Fluent. Zip file, 6.63 GB.
suction_model_PP&SVW2018_a2.zip.001
CFD model a2 PART2/7
suction_model_PP&SVW2018_a2.zip.002
CFD model a2 PART3/7
suction_model_PP&SVW2018_a2.zip.003
CFD model a2 PART4/7
suction_model_PP&SVW2018_a2.zip.004
CFD model a2 PART5/7
suction_model_PP&SVW2018_a2.zip.005
CFD model a2 PART6/7
suction_model_PP&SVW2018_a2.zip.006
CFD model a2 PART7/7
suction_model_PP&SVW2018_a2.zip.007
CFD models c1 and c2 PART1/5
Ansys 19.0 Workbench project file that contains the model and data for the simulation described in the article as "model c1" and "model c2". Raw data files can be found under /dp0/FFF-2/Fluent, /dp0/FFF-3/Fluent. Zip file, 4.09 GB.
suction_model_PP&SVW2018_c1_c2.zip.001
CFD models c1 and c2 PART2/5
suction_model_PP&SVW2018_c1_c2.zip.002
CFD models c1 and c2 PART3/5
suction_model_PP&SVW2018_c1_c2.zip.003
CFD models c1 and c2 PART4/5
suction_model_PP&SVW2018_c1_c2.zip.004
CFD models c1 and c2 PART5/5
suction_model_PP&SVW2018_c1_c2.zip.005