Hello Everyone,
I am fairly new to COMSOL Multyphysics and I would appreciate any help.** I am using COMSOL Multiphysics 5.3a**. I am trying to model the 2D-fuid flow (convection and diffusion) of a molecule in a simple microfluidic device. The idea is that the device channel and chambers will be completely filled with water. Then a droplet of water containing this time, the molecule, with a diffusion coefficient of (Dij = 2.0e-10m^2/s) is added in one of the chambers of the device. This droplet is supposed to have an initial velocity of 9.0e-8m/s, simulating the velocity of a droplet coming out of a micropipette, once ejected. Once the droplet is ejected with that initial velocity, the molecule will be driven by convection as well as diffusion; however, it will lose velocity as time passes, reaching to a diffusion dominant flow. I have tried using coupling flow, laminar flow for the already existing fluid in the device, and transport of diluted species for the molecule. However, I am not sure how to:
1) Add the step function for the initial time condition, where the droplet is released for 1 second and then stops; and whatever volume of this droplet is the one flowing through the device. 2) Give an initial condition for the velocity of the droplet ( 9e-8m/s)
Attached is a google drive link to the file as well as a picture of the system. The picture features a circle in one of the chambers, which is supposed to simulate the droplet.
- The file is for the 2D simulation of diffusion only, or that is what I am understanding of my simulation since I have not figured out how to add the initial velocity of the droplet.
Link: https://drive.google.com/open?id=1e9oXF3ScliLeo517DmeYADC4zjrtszQ8
Thank you in advance!,
Juan Pena M.Sc. Biomedical Engineering Student