Numerical methods are a great help in designing processes and their further optimisation. Recently, the lattice Boltzmann method has been growing in popularity as an alternative to other mesoscopic methods used in microfluidics. It can be used for simple simulations of fluid flow in a channel as well as for more complex simulations of multiphase systems, chemical reactions or heat transfer.
In my thesis I developed a Fortran code for the lattice Boltzmann method. I used the code to simulate 2D fluid flow in a microchannel with triangular inlet zone containing pillars. I studied effects of microchannel height, length of the inlet zone, size and position of pillars on fluid distribution at the main zone of the microchannel. With two different pillar sizes I made four different layouts for two different inlet geometries and compared them all together.
I achieved optimal results with the microchannel with a longer inlet, a dense arrangement of smaller pillars and a lower microchannel height. This results in a more homogenous distribution of the liquid, the velocity profile in the main part of the microchannel establishes more quickly. In the case of only larger pillars or combinations of both pillar sizes, the distribution is worse and the velocity profile establishes more slowly, further from the start of the main part of the microchannel. The choice of Reynolds number is also important, there is a trade-off between a high enough velocity to make the system suitable for chemical reactions and a low enough velocity so it does not have a major impact on poorer liquid distribution and establishment of the velocity profile.
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