DOI: 10.5061/dryad.4j0zpc8mt
title: Data from: Asymmetric fluid flow in helical pipes inspired by shark intestines

description: Unlike human intestines, which are long, hollow tubes, the intestines of
 sharks and rays contain interior helical structures surrounding a
 cylindrical hole. One function of these structures may be to create
 asymmetric flow, favoring passage of fluid down the digestive tract, from
 anterior to posterior. Here, we design and 3D print biomimetic models of
 shark intestines, in both rigid and deformable materials. We use the rigid
 models to test which physical parameters of the interior helices (the
 pitch, the hole radius, the tilt angle, and the number of turns) yield the
 largest flow asymmetries. These asymmetries exceed those of traditional
 Tesla valves, structures specifically designed to create flow asymmetry
 without any moving parts. When we print the biomimetic models in
 elastomeric materials so that flow can couple to the structure’s shape,
 flow asymmetry is significantly amplified; it is 7-fold larger in
 deformable structures than in rigid structures. Last, we 3D-print
 deformable versions of the intestine of a dogfish shark, based on a
 tomogram of a biological sample. This biomimic produces flow asymmetry
 comparable to traditional Tesla valves. The ability to influence the
 direction of a flow through a structure has applications in biological
 tissues and artificial devices across many scales, from large industrial
 pipelines to small microfluidic devices. 
description: # Asymmetric fluid flow in helical pipes inspired by shark intestines
 [https://doi.org/10.5061/dryad.4j0zpc8mt](https://doi.org/10.5061/dryad.4j0zpc8mt) This dataset supplements our paper "Asymmetric fluid flow in helical pipes inspired by shark intestines", and includes all the results needed to support our conclusions. It contains all 3D structures (in STL format) of the helical pipes used in the paper and all our measurements of their hydraulic properties (in CSV format). ## Description of the data and file structure **STL files:** * **Biomimetic helical pipes**: The filename of each STL file is formatted as "SimplifiedModel_*[Rigid/Soft]*_p[pitch values]*_rHole*[hole radius]*_a*[angle tangent]*_nTurn]*.STL". Note that Rigid / Soft models are identical, and this tag was added to indicate the soft (deformable) pipes used in this study. There are a total of 26 rigid pipe models and 4 soft pipe models. * **Deformed helical pipes**: the deformed inner helical membranes (under a uniform load of 350Pa) are in a single file - "deformed_uniform_load_p7.5_r10_rHole3_a1.5_nTurn1.5_t0.5_E1MPa_P350Pa.STL" * **Shark intestines analogs**: STL files of the reconstructed CT scans of the spiral shark intestines (*Centroscyllium nigrum*): "CTscan_&lt;*portion*&gt;STL" were used in the supplementary information (SI Section 5, Fig. S10). They will be made available on request (not uploaded to Dryad since the CC0 license waiver does not apply to them). CT scan of the spiral intestines of Centroscyllium nigrum was downloaded from MorphoSource: S Leigh, LACM:Fish:11156.001 Centroscyllium nigrum (2020). [https://www.morphosource.org/concern/media/000168189](https://www.morphosource.org/concern/media/000168189) **CSV files** * **Raw_rigid.CSV**: A table of all the raw results for all the rigid pipes. Each row corresponds to a single measurement, including the parameters of the pipe, its orientation (1: up, -1:down), the measured flow rates, and the calculated effective length. * **Di_rigid.CSV**: A table of all the analyzed diodicities for the rigid pipe. Each row corresponds to a single experiment. * **Di_soft.CSV**: A table of all the results for the deformable pipes. Each row corresponds to a single measurement, including the parameters of the pipe, its orientation (1: up, -1:down), the measured flow rates, and calculated effective length, and diodicity. Note that diodicity is defined only for data in the reverse direction, hence its entries for the down (-1) direction are kept empty. ## Code/Software 3D structures were rendered via home-build code in *Wolfram* *Mathematica* 13.1. The code will be shared upon request.