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Gas stratification model
Posted 2016年3月7日 GMT-5 12:17 Fluid & Heat Version 5.1 0 Replies
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I recently started using COMSOL, and I am having a lot of problems with a model that, in theory, should be extremely easy.
I need to model the stratification of a mixture of oxygen and helium in a closed vessel, due to gravity.
I used a Laminar Flow physic (to use a Volume Force, dependent on local density), and a Transport of Concentrated species, to get a value for the density. Boundary conditions are pretty easy - walls and no flux everywhere. Since I am interested in a proof of concept for stratification, I set the diffusion coefficient to 0 (once the model works, I will modify that, of course). I used a linear function of the height of the vessel as initial condition for the mass fraction of oxygen, so I have a different effect of gravity from the start.
With this model, I incur in the following error:
Failed to find consistent initial values.
Last time step is not converged.
- Feature: Time-Dependent Solver 1 (sol1/t1)
I even tried to switch the transport of concentrated species to the transprt of diluted species, using a variable tied to the concentration to account for the density difference . Same identical error.
I really have no idea how to solve this problem, any help will be greatly appreciated.
Hello Nicola Zanetti
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