# Injection of Deformable Capsules in a Reservoir, a Systematic Analysis

## TL;DR

This study computationally investigates how deformable capsules eject from a narrow channel into a reservoir, analyzing the effects of capsule size, deformability, and channel dimensions on fluid dynamics and capsule interactions.

## Contribution

It provides a systematic analysis of capsule motion, deformation, and fluid response in a novel flow setup not previously covered in literature.

## Key findings

- Capsule interactions significantly influence local velocity fields.
- Membrane deformability affects inter-capsule interactions.
- The ratio of capsule diameter to channel diameter is a key factor.

## Abstract

A computational study of capsule ejection from a narrow channel into a reservoir is undertaken for a combination of varying deformable capsule sizes and channel dimensions. A mass spring membrane model is coupled to an Immersed Boundary Lattice Boltzmann model solver. The aim of the present work is the description of the capsules motion, deformation and the response of the fluid due to the complex particle dynamics. The interactions between the capsules affect the local velocity field significantly and are responsible for the dynamics observed. Capsule membrane deformability is also seen to affect inter capsule interaction, and we observe that the train of three particles locally homogenizes the velocity field and the leading capsule travels faster than the other two trailing capsules. On the contrary, variations in size of the reservoir do not seem to be relevant, while the ratio of capsule diameter with respect to channel diameter plays a major role as well as the ratio of capsule diameter to inter capsule spacing. This flow set up has not been covered in the literature, and consequently we focus on describing capsule motion, membrane deformation and fluid dynamics, as a preliminary investigation in this field.