DOI: 10.5061/dryad.280gb5n0s
title: Filter feeding in devil rays is highly sensitive to morphology

description: Mobulid rays (manta and devil rays) use a highly-specialized filtering
 apparatus to separate plankton food particles from large volumes of
 seawater. Recent studies have indicated that captive vortices form within
 the microscale pores of the filter, which enhance filtration efficiency
 through a novel mechanism referred to as ricochet separation. The high
 throughput and clog resistance of this filtration process has garnered the
 attention of the engineering community and inspired the development of
 several engineered filtration systems. However, it is still unclear how
 changes to the filter morphology influence the surrounding flow patterns
 and filtration efficiency. We address this question by examining the flow
 fields around and filtering properties of mobulid filters with
 systematically varied morphologies, using a combination of computational
 fluid dynamics and experiments on physical models. Our results indicate
 that the morphological features critical to the performance of the mobulid
 filtering structure are substantially different from those expected for a
 conventional sieve filter. While the pore size is the principal
 determinant of the size-dependent filtration efficiency in a sieve filter,
 we found that the captive vortices in a mobulid filter grow or shrink to
 fill the pore, and changes in the pore size have relatively little effect
 on filtration efficiency. In contrast, the filtration efficiency appears
 to be highly sensitive to the orientation of the filter lobes (microscale
 plate-like structures). These results provide a foundation for
 interpreting the morphological differences between species and also for
 generating optimized bioinspired designs.
description: The deposited material provides the scripts and models used for
 computational fluid dynamics (CFD) simulations and particle image
 velocimetry (PIV) experiments. Further details may be found in the
 associated research article.
description: # Filter feeding in devil rays is highly sensitive to morphology
 [https://doi.org/10.5061/dryad.280gb5n0s](https://doi.org/10.5061/dryad.280gb5n0s) ## Description of the data and file structure Computational fluid dynamics (CFD) simulations and particle image velocimetry (PIV) experiments examining the biomechanics software filter feeding in devil rays. ### Files and variables #### File: kahane\_rapport\_etal\_2024.tar.gz **Description:** Scripts and model files for CFD and PIV, organized as * cfd_models : input files for CFD simulations * freestream_vel : simulations varying freestream velocity * lobe_angle_offset : simulations varying lobe angle * lobe_period : simulations varying lobe period * lobe_tip_angle_offset : simulations varying lobe tip angle * lobe_tip_length : simulations varying lobe tip length * lobe_tip_radius : simulations varying lobe tip radius * cfd_scripts : MATLAB scripts for generating CFD input files * analyze_trace_rev.m : analyze time-reversed fluid trajectories * calc_percent_filtered.m : calculate percentage of particles 'filtered' * calc_solid_trace_results.m : calculate particle filtration for simulation series * calc_trace_rev_results.m : calculate time-reversed fluid trajectories for simulation series * generate_model_initial.m : write CFD input file for initial simulation * generate_model_restart.m : write CFD input file for restart simulation * generate_model_spoiler_basic_config : generate model configuration for spoiler-like lobes * generate_model_wing_basic_config : generate model configuration for wing-like lobes * generate_run_trace_batch_script.m : generate batch processing script for particle tracing * generate_trace_params_solids.m : generate parameters file for particle tracing * particle_sim : source code for particle tracing simulations * build : build folder for code * c_source : source code for library * Makefile : build script for library * zargs : command-line processing library * piv_scripts : scripts for DPIV analysis * osiv_corr_params.txt : parameters file for osiv_corr * processRawResults.m : MATLAB file for processing DPIV results