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Questions about flux in transport of dilute species

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Hi fellow COMSOLers!

I'm building a semiconductor quantum well model using electrostatics together with transport of dilute species (TDS). I use one TDS for the main electron population outside the well and one TDS model for the electron population inside the quantum well. I want to model the exchange between these two electron populations using flux due to thermionic emission into and out of the quantum well. I am using flux nodes at the boundary between the different regions in order to implement this behavior.

I am having problems understanding how the flux works in the TDS. Even with all flux disabled (and a 'no flux' default node active on all boundaries), if I plot 'normal total flux' along the boundaries, this is not zero but instead a large number. Since the 'no flux' node is the only specified flux in the TDS models, shouldn't the flux normal to the boundary be zero?

More generally, if I plot the flux normal to any boundary to the region where the 'no flux' node is active, I do get a finite flux.

How do I implement a flux through the boundary that is set specifically by my expression for thermionic emission?

Best,
Kristian

0 Replies Last Post 2011年11月4日 GMT-4 04:55
COMSOL Moderator

Hello Kristian Storm

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