  This study aims to investigate the behavior of multicomponent fluid flows
consisting of Newtonian and non-Newtonian components, especially terminal
velocity of a rising bubble in a power-law fluid. A recent lattice Boltzmann
(LB) model is extended using power-law scheme to be able to simulate both
Newtonian and non-Newtonian fluid flows at high density and viscosity ratios.
Also, a variable mobility is introduced in this study to minimize the
unphysical error around small bubbles in the domain. A three-component fluid
flow system is examined using a constant and variable mobility. It is shown
that each component has more stability using variable mobility while constant
mobility causes interface dissipation, leading to mass loss gradually. In
addition, two test cases including power-law fluid flows driven between two
parallel plates are conducted to show the accuracy and capability of the model.
To find a grid-independent computational domain, a grid independency test is
carried out to show that a 200*400 domain size is suitable for our
computations. Then, terminal velocity of a rising bubble is compared to an
existing correlation in the literature, indicating that the results are in good
agreement with existing study so that average relative error in six different
cases is 5.66 %. Also, the simulated examples show good conformity to
experimental results over a range of the Reynolds and Eotvos numbers.
