Inflow and outflow boundary conditions for 2D suspension simulations with the immersed boundary lattice Boltzmann method

Victor W Azizi Tarksalooyeh,Gábor Závodszky,Britt J M Van Rooij,Alfons G Hoekstra

doi:10.1016/j.compfluid.2018.04.025

Victor W Azizi Tarksalooyeh, Gábor Závodszky + Show 2 more

Open Access

https://doi.org/10.1016/j.compfluid.2018.04.025

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Journal: Computers & Fluids	Publication Date: Apr 22, 2018
Citations: 20	License type: cc-by

Affiliation: University of Amsterdam, ITMO University

Abstract

In- and outflow boundary conditions for 2D immersed boundary lattice Boltzmann suspension simulations, applied to cell based blood flow models, are presented. The inlet is constructed with an one-way coupling to a periodic domain containing a correct distribution of suspended particles. This provides an inflow of particles that has a correct distribution and is decoupled from any phenomena in the flow domain. An outflow boundary for the particles that does not influence the distribution of particles in the flow domain is also constructed. With this a method to run long ( > 1 s) cell based blood flow simulations within any type of domain is provided. These boundary conditions are then used for a simulation of blood flow in a curved vessel with an aneurysm.

Highlights

Cell resolved blood flows are studied with various computer models, see e.g. Fedosov et al [1] or Mountrakis et al [2]
In this paper inflow and outflow flow boundaries for complex flows are constructed for suspensions that are modeled with an immersed boundary method [7] on top of a lattice Boltzmann fluid solver [8]
The geometries only differ in length in the direction of the periodic boundary condition (Lp), giving them different aspect ratios defined as the length of a channel divided by its width (Lp/Ld)

Summary

Introduction

Cell resolved blood flows are studied with various computer models, see e.g. Fedosov et al [1] or Mountrakis et al [2]. These models explicitly represent the red blood cells and/or platelets in their model [3] to mimic and explain various effects (e.g. the Fåhræus–Lindqvist effect [4] or thrombus formations [5]) In these studies mostly periodic boundary conditions (PBC) are used for the flow domain. In this paper inflow and outflow flow boundaries for complex flows are constructed for suspensions that are modeled with an immersed boundary method [7] on top of a lattice Boltzmann fluid solver [8] These boundaries are important since the distribution of cells in a blood vessel is non-trivial. In a system with PBC the outlet can influence the distribution of particles in the inlet boundary condition (e.g. imagine a thrombus where all platelets get stuck, this directly causes a depletion of active platelets)

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