Hydrostatic pressure-driven flows through soft tissues and gels cause deformations of the solid network to occur, due to drag from the flowing fluid. This phenomenon occurs in many contexts including physiological flows and infusions through soft tissues, in mechanically stimulated engineered tissues, and in direct permeation measurements of hydraulic permeability. Existing theoretical descriptions are satisfactory in particular cases, but none provide a description which is easy to generalize for the design and interpretation of permeation experiments involving a range of different boundary conditions and gel properties. Here a theoretical description of flow-induced permeation is developed using a relatively simple approximate constitutive law for strain-dependent permeability and an assumed constant elastic modulus, using dimensionless parameters which emerge naturally. Analytical solutions are obtained for relationships between fundamental variables, such as flow rate and pressure drop, which were not previously available. Guidelines are provided for assuring that direct measurements of hydraulic permeability are performed accurately, and suggestions emerge for alternative measurement protocols. Insights obtained may be applied to interpretation of flow-induced deformation and related phenomena in many contexts.
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http://dx.doi.org/10.1115/1.4023095 | DOI Listing |
Invest Ophthalmol Vis Sci
November 2024
Mechanical and Aerospace Engineering Department, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States.
Purpose: To present a first principle-based, high-fidelity computational model for predicting full three-dimensional (3D) and time-resolved retinal microvascular hemodynamics taking into consideration the flow and deformation of individual blood cells.
Methods: The computational model is a 3D fluid-structure interaction model based on combined finite volume/finite element/immersed-boundary methods. Three in silico microvascular networks are built from high-resolution in vivo motion contrast images of the superficial capillary plexus in the parafoveal region of the human retina.
Macromolecules
October 2024
Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States.
Polyolefins, including high-density polyethylene (HDPE) and isotactic polypropylene (iPP), account for over half of the worldwide plastics market and have wide-ranging applications. Recycling of these materials is hindered due to separation difficulties as co-mingled blends of HDPE and iPP often exhibit brittle mechanical behavior because phase separated domains detach under stress due to low interfacial adhesion. Motivated to improve mechanical properties of mixed recyclates during processing, this work examines the effect of shear on the crystallization kinetics and rheological properties of HDPE-iPP blends utilizing a combination of differential scanning calorimetry (DSC), rheo-Raman spectroscopy, polarized optical microscopy, and scanning electron microscopy (SEM).
View Article and Find Full Text PDFProc Natl Acad Sci U S A
October 2024
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138.
Sci Adv
September 2024
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
Shape-morphing displays alter their surface geometry to convey information through three-dimensional shapes. However, rapid transformation into seamless shapes with multimodal tactile sensations poses challenges. Here, we introduce a versatile soft shape-morphing and tactile display, using a novel actuator that combines a PVC gel composite, dielectric liquid, and an electrode array.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
October 2024
Department of Chemistry, University of Washington, Seattle, WA 98195.
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.
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