Numerical simulation on the effects of the viscosity contrast of a soft particle at the transition between tank-treading and tumbling motions

Abstract

In general, suspensions, which refer to a heterogeneous mixture of a solid in a liquid, are used in a variety of fields, such as in industrial and medical applications. Despite the fact that there is a plethora of studies performed on suspensions, there are several rheological issues that remain unresolved, clearly suggesting that it is critical to elucidate the rheological properties of suspensions. Many studies on suspensions, especially of red blood cells, have been carried out in the past. Although various experimental studies have been carried out, it is difficult to establish a causal relationship between the mechanical properties of the particles, such as membrane elasticity and membrane viscosity, and the properties of the suspension, such as effective viscosity by experimentation, as the parameters which determine the flow properties of the suspension are numerous and complicated (Fischer et al., 1978;Pozrikidis, 2005;Tomaiuolo et al., 2009). However, numerical simulations are considered effective as the values of the parameters which determine the mechanical properties of the particles can be easily changed. While various numerical methods were proposed, the lattice Boltzmann method used in this study has been used in much research, as it is a simple algorithm and suitable for parallel computation (