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Kou W, Acharya S, Halder S, Patankar N, Pandolfino J. Study Biophysics of Esophageal Transport by Combining Simulation, Modeling and Bio-Mechanical Analysis Based on In-Vivo Data. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Sprinkle B, Donev A, Bhalla APS, Patankar N. Brownian dynamics of fully confined suspensions of rigid particles without Green's functions. J Chem Phys 2019; 150:164116. [PMID: 31042913 DOI: 10.1063/1.5090114] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We introduce a Rigid-Body Fluctuating Immersed Boundary (RB-FIB) method to perform large-scale Brownian dynamics simulations of suspensions of rigid particles in fully confined domains, without any need to explicitly construct Green's functions or mobility operators. In the RB-FIB approach, discretized fluctuating Stokes equations are solved with prescribed boundary conditions in conjunction with a rigid-body immersed boundary method to discretize arbitrarily shaped colloidal particles with no-slip or active-slip prescribed on their surface. We design a specialized Split-Euler-Maruyama temporal integrator that uses a combination of random finite differences to capture the stochastic drift appearing in the overdamped Langevin equation. The RB-FIB method presented in this work only solves mobility problems in each time step using a preconditioned iterative solver and has a computational complexity that scales linearly in the number of particles and fluid grid cells. We demonstrate that the RB-FIB method correctly reproduces the Gibbs-Boltzmann equilibrium distribution and use the method to examine the time correlation functions for two spheres tightly confined in a cuboid. We model a quasi-two-dimensional colloidal crystal confined in a narrow microchannel and hydrodynamically driven across a commensurate periodic substrate potential mimicking the effect of a corrugated wall. We observe partial and full depinning of the colloidal monolayer from the substrate potential above a certain wall speed, consistent with a transition from static to kinetic friction through propagating kink solitons. Unexpectedly, we find that particles nearest to the boundaries of the domain are the first to be displaced, followed by particles in the middle of the domain.
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Affiliation(s)
- Brennan Sprinkle
- Engineering Science and Applied Math, Northwestern University, Evanston, Illinois 60208, USA
| | - Aleksandar Donev
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA
| | - Amneet Pal Singh Bhalla
- Department of Mechanical Engineering, San Diego State University, San Diego, California 92182, USA
| | - Neelesh Patankar
- McCormick School of Engineering, Northwestern University, Evanston, Illinois 60208, USA
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Abstract
An extreme water-repellent surface is designed and fabricated with a hierarchical integration of nano- and microscale textures. We combined the two readily accessible etching techniques, a standard deep silicon etching, and a gas phase isotropic etching (XeF2) for the uniform formation of double roughness on a silicon surface. The fabricated synthetic surface shows the hallmarks of the Lotus effect: durable super water repellency (contact angle>173 degrees) and the sole existence of the Cassie state even with a very large spacing between roughness structures (>1:7.5). We directly demonstrate the absence of the Wenzel's or wetted state through a series of experiments. When a water droplet is squeezed or dropped on the fabricated surface, the contact angle hardly changes and the released droplet instantly springs back without remaining wetted on the surface. We also show that a ball of water droplet keeps bouncing on the surface. Furthermore, the droplet shows very small contact angle hysteresis which can be further used in applications such as super-repellent coating and low-drag microfludics. These properties are attributed to the nano/micro surface texture designed to keep the nonwetting state energetically favorable.
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Affiliation(s)
- Yongjoo Kwon
- School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1, Sillim, Gwanak, Seoul, Korea 151-742
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Liu WK, Liu Y, Farrell D, Zhang L, Wang XS, Fukui Y, Patankar N, Zhang Y, Bajaj C, Lee J, Hong J, Chen X, Hsu H. Immersed finite element method and its applications to biological systems. Comput Methods Appl Mech Eng 2006; 195:1722-1749. [PMID: 20200602 PMCID: PMC2830735 DOI: 10.1016/j.cma.2005.05.049] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
This paper summarizes the newly developed immersed finite element method (IFEM) and its applications to the modeling of biological systems. This work was inspired by the pioneering work of Professor T.J.R. Hughes in solving fluid-structure interaction problems. In IFEM, a Lagrangian solid mesh moves on top of a background Eulerian fluid mesh which spans the entire computational domain. Hence, mesh generation is greatly simplified. Moreover, both fluid and solid domains are modeled with the finite element method and the continuity between the fluid and solid subdomains is enforced via the interpolation of the velocities and the distribution of the forces with the reproducing Kernel particle method (RKPM) delta function. The proposed method is used to study the fluid-structure interaction problems encountered in human cardiovascular systems. Currently, the heart modeling is being constructed and the deployment process of an angioplasty stent has been simulated. Some preliminary results on monocyte and platelet deposition are presented. Blood rheology, in particular, the shear-rate dependent de-aggregation of red blood cell (RBC) clusters and the transport of deformable cells, are modeled. Furthermore, IFEM is combined with electrokinetics to study the mechanisms of nano/bio filament assembly for the understanding of cell motility.
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Affiliation(s)
- Wing Kam Liu
- Department of Mechanical Engineering, 2145 Sheridan Road, Northwestern University, Evanston, IL 60208, United States
- Corresponding author. Tel.: +1 847 491 7094; fax: +1 847 491 3915. (W.K. Liu)
| | - Yaling Liu
- Department of Mechanical Engineering, 2145 Sheridan Road, Northwestern University, Evanston, IL 60208, United States
| | - David Farrell
- Department of Mechanical Engineering, 2145 Sheridan Road, Northwestern University, Evanston, IL 60208, United States
| | - Lucy Zhang
- Department of Mechanical Engineering, Tulane University, 6823 Saint Charles Avenue, New Orleans, LA 70118, United States
| | - X. Sheldon Wang
- Department of Mathematical Sciences, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, United States
| | - Yoshio Fukui
- Department of Mechanical Engineering, 2145 Sheridan Road, Northwestern University, Evanston, IL 60208, United States
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, United States
| | - Neelesh Patankar
- Department of Mechanical Engineering, 2145 Sheridan Road, Northwestern University, Evanston, IL 60208, United States
| | - Yongjie Zhang
- Institute for Computational Engineering and Sciences, Department of Computer Sciences, The University of Texas at Austin, Austin, TX 78712, United States
| | - Chandrajit Bajaj
- Institute for Computational Engineering and Sciences, Department of Computer Sciences, The University of Texas at Austin, Austin, TX 78712, United States
| | - Junghoon Lee
- School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1 Shinlim, Kwanak, Seoul 151-742, Republic of Korea
| | - Juhee Hong
- School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1 Shinlim, Kwanak, Seoul 151-742, Republic of Korea
| | - Xinyu Chen
- Department of Mechanical Engineering, 2145 Sheridan Road, Northwestern University, Evanston, IL 60208, United States
| | - Huayi Hsu
- Department of Mechanical Engineering, 2145 Sheridan Road, Northwestern University, Evanston, IL 60208, United States
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