Discussion Forum

Hi,

I am modelling microfluidic devices in Comsol 5.5 using the laminar flow module in a 3D geometry. Said devices are working in a "passive" regime, ie. no external pressure source : fill the inlet well with fluid and let the pressure difference between the inlet (full) and oulet (empty) well do its magic. I am trying to model the evolution of the pressure field in the device.

I first tried using a level-set model, setting up an interface between the liquid and the exterior (air) to see the water level go down in the inlet well and rise in the outlet well (until equilibrium of course). The computing time skyrocketted unfortunately, so I would like to try something else.

I am under the impression that I should be able to accurately model this situation by simply setting the right pressure difference between the inlet well and the rest of the device at t0, without setting up any inlet or outlet (nothing is effectively getting in or out of the device, fluid is only moving from one compartment to an other). However, the results I obtain are really off.

Is this the wrong way to do it entirely, or am I just setting it up wrong ? I am only interested in the evolution of the pressure field, modelling the interface is of no importance to me.

I am not very well versed in CFD, but I can provide more detailled info if needed.

Thanks !