(160d) Motion of a Deformable Drop in Microchannels of Complex Shape
AIChE Annual Meeting
2017
2017 Annual Meeting
Engineering Sciences and Fundamentals
Microfluidic and Nanoscale Flows: Multiphase and Fields
Monday, October 30, 2017 - 1:15pm to 1:30pm
The drop size is comparable (or close) to the width of the narrowest branch sections, but is generally much smaller than the overall channel domain size. This difference in the scales makes it difficult to address the problem by a standard boundary-integral (BI) algorithm (or other approaches) for the entire domain due to necessary resolution on the drop and the local vicinity as the drop proceeds through the channel, resulting in a very large total number of BI elements. Instead, we adapt the idea of the âmoving frameâ BI method [2]. Namely, the drop is embedded in a dynamically constructed computational cell (moving frame, MF) and the 3D BI problem is solved in the cell only, with the outer boundary conditions for the fluid velocity provided by the 2D flow that would exist in the channel without the drop. The MF cell is obtained by intersecting a cubic box around the drop with the entire channel domain, and it can acquire quite complex shapes as the drop proceeds. Parts of the MF boundary may be inside the flow domain, while other parts may belong to the channel walls, so our method captures strong drop-wall hydrodynamical interactions. The cutting box has an intermediate size, several times larger than the non-deformed drop but typically much smaller than the overall channel domain, thus resulting in many-fold computational savings compared to the standard approach. Robustness of the proposed algorithm is further demonstrated by an example of tight drop motion through a multiple bifurcation system (akin to those in experiments [3]).
[1] Nakashima M., Yamada M. and Seki M. 2004 âPinched flow fractionation (PFF) for continuous particle separation in a microfluidic deviceâ, in proceedings of 17thIEEE International Conference on Micro Electro Mechanical Systems, Maastricht, The Netherlands (Piscataway, NJ), pp. 33-36.
[2] Zinchenko A.Z., Ashley J.F. and Davis R.H. 2012 âA moving-frame boundary-integral method for particle transport in microchannels of complex shapeâ. Phys. Fluids, vol. 24, 043302.
[3] Roberts B.W. and Olbricht W.L. 2006 âThe distribution of freely suspended particles at microfluidic bifurcationsâ. AIChE J., vol. 52, pp.199-206.