Fixed-mesh approach for different dimensional solids in fluid flows : application to biological mechanics

S. Miyauchi, A. Ito, S. Takeuchi and T. Kajishima, "Fixed-mesh approach for different dimensional solids in fluid flows : application to biological mechanics", Journal of Mechanical Engineering and Sciences, Vol. 6, pp.818-844, UMP, 201

Lubrication pressure model in a non-negligible gap for fluid permeation through a membrane with finite permeability

Shintaro Takeuchi, Toshiaki Fukada, Shuji Yamada, Suguru Miyauchi, and Takeo Kajishima, "Lubrication pressure model in a non-negligible gap for fluid permeation through a membrane with finite permeability", Physical Review Fluids, 6(11), 114101, https://doi.org/10.1103/PhysRevFluids.6.114101

Fluid permeation through a membrane with infinitesimal permeability under Reynolds lubrication

This article has been published in a revised form in Journal of Mechanics [https://doi.org/10.1017/jmech.2020.38]. This version is published under a Creative Commons CC-BY-NC-ND. No commercial re-distribution or re-use allowed. Derivative works cannot be distributed. © 2020 The Society of Theoretical and Applied Mechanics

Fixed-mesh approach for different dimensional solids in fluid flows : application to biological mechanics

For simulations of biological flows, our original immersed solid method and feedback immersed boundary method are coupled to deal with the interaction between a fluid and solids of different dimensional topologies. The mesh used in both methods is non-conforming with respect to the fluid-solid interface, and the coupled approach facilitates the handling of the fluid-structure interaction including large deformation of the solids. We show the validity of our method through simulations of static and dynamic benchmark problems. The results of the simulations confirmed that our method has a first order accuracy and shows good agreement with the strong coupling method reported in the literature. As for examples of biological flow, the expiratory flow through vocal cords and pulsative flow through an elastic channel with fibers are analyzed. For the flow through vocal cords, the vocal cords exhibit different vibration modes depending on the initial clearance of the vocal cords, regardless of the contacts of the vocal cords. For the flow through the elastic channel with fibers, fibers decrease the wall shear stress, and the elasticity of the wall enhances the reduction of the wall shear stress.S. Miyauchi, A. Ito, S. Takeuchi and T. Kajishima, "Fixed-mesh approach for different dimensional solids in fluid flows : application to biological mechanics", Journal of Mechanical Engineering and Sciences, Vol. 6, pp.818-844, UMP, 201

Transport of solute and solvent driven by lubrication pressure through non-deformable permeable membranes

A discrete-forcing immersed boundary method with permeable membranes is developed to investigate the effect of lubrication on the permeations of solute and solvent through membrane. The permeation models are incorporated into the discretisation at the fluid cells including the membrane, and discretised equations for the pressure Poisson equation and convection–diffusion equation for the solute are represented with the discontinuities at the membrane. The validity of the proposed method is established by the convergence of the numerical results of the permeate fluxes (solute and solvent) to higher-order analytical models in a lubrication-dominated flow field. As a model of the mass exchange between inside and outside of a biological cell flowing in a capillary, a circular membrane is placed between parallel flat plates, and the effect of lubrication is investigated by varying the distance between the membrane and the walls. The pressure discontinuity near the wall is larger than that at the stagnation point, which is a highlighted effect of lubrication. In the case of a small gap, the solute transport is dominated by convection inside the circular membrane and by diffusion outside. Through the time variation of the concentration in the circular membrane, lubrication is shown to enhance mass transport from/to inside and outside the membrane.Yamada, S., Takeuchi, S., Miyauchi, S. et al. Transport of solute and solvent driven by lubrication pressure through non-deformable permeable membranes. Microfluid Nanofluid 25, 83 (2021). https://doi.org/10.1007/s10404-021-02480-5

Numerical Study of Pressure Response to Action Potential by Water Permeation With Ion Transports

Matsuyama Haruhi, Fujii Takehiro, Miyauchi Suguru, et al. Numerical Study of Pressure Response to Action Potential by Water Permeation With Ion Transports. ASME Journal of Heat and Mass Transfer 146, 710 (2024); https://doi.org/10.1115/1.4065675.While the permeation mechanism of solute (e.g., ions and glucose) through biological membrane has been studied extensively, the mechanical role of water transport in intracellular phenomena has not received much attention. In the present study, to investigate the effect of water permeation on the intracellular pressure response, a novel permeation flux model through a biological membrane is developed by incorporating the coupling permeabilities (between water and ion fluxes) as the water–ion interaction in the ion channels. The proposed model is applied to a two–dimensional permeation problem of water and ions in a closed cell separated by a thin membrane. The permeation flux model reproduces the typical time response of intracellular pressure to action potentials with reasonable agreement with experimental results in the literature, indicating that the pressure response can be characterized by the following three parameters: water permeability, the mass ratio of water and ion, and the ratio of the permeation fluxes of water and ion. In particular, the permeation flux ratio plays an essential role in intracellular phenomena; depending on the value of the permeation flux ratio, the time lag between the action potential and the pressure response is 0.1 times smaller than that expected by the previous researchers, indicating that water transport associated with ions may trigger a pressure response. This study demonstrates the importance of water permeation in intracellular mechanical response through coupling of the fluid motion and electric fields