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Hydrodynamic focusing model appears to have excessive diffusion

Posted Jun 15, 2017, 2:38 p.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD), Microfluidics Version 5.2a 0 Replies

Chloe Yang
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I'm using the laminar flow and transport of dilute substances modules to model hydrodynamic focusing of a sample flow. I have two side inlets for water (concentration of 0 M) and one inlet with dissolved substance (concentration 0.01 M) at flow rates 50 ul/min (sheathing flow) and 10 ul/min (sample flow). The concept is similar to this (see page 2): www.comsol.com/paper/download/210991/mehendale_paper.pdf

From imaging of the actual device with the same flow rates, I know the sample beam profile is more defined, and separate flows are maintained throughout the device with very little mixing (this is also visualized in the model used by the paper above).

However, in my model, my sample substance appears to completely diffuse into the surrounding water sheath flow, and it is completely mixed into the sheath flow by the outlet. This result is not what I anticipated, nor is it what I have observed.

The file for my model can be found here: drive.google.com/open?id=0B8p0w5pyDH5eTm5vN3NYVWFQUlk

I appreciate any help!
0 Replies Last Post Jun 15, 2017, 2:38 p.m. EDT
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Hello Chloe Yang

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