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Electrokinetic....Convective flux
Posted Jan 14, 2011, 11:32 a.m. EST MEMS & Nanotechnology, Fluid & Heat, MEMS & Piezoelectric Devices, Microfluidics, Chemical Reaction Engineering 1 Reply
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Hi all,
I am trying to model Electrokinetic flow in nanochannels. At the exit of nanochannel, I would like to implement this type of Boundary condition : n.(-z*u*F*ci*grad(V))=0.
I know that the Comsol has the "Convective Flux" boundary condition as follows: n.(-Dgrad(ci)-z*u*F*ci*grad(V))=0.
Would you please tell me how I can change it to n.(-z*u*F*ci*grad(V))=0
Thank you in advance,
Saeid
1 Reply Last Post Jan 14, 2011, 3:38 p.m. EST
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Posted:
1 decade ago
Hi
I would say ideally you should either rewrite the full physics of your COMSOL model, or at least be sure you understand in detail what is happening behind in COMSOL (for your case I cannot say I know "exactly" ;),
or you could try a crude way to edit the equations, in equation view by changing:
n.(-Dgrad(ci)-z*u*F*ci*grad(V))=0. into n.(-0*Dgrad(ci)-z*u*F*ci*grad(V))=0.
This will "lock" the equations and you must reset them manually if you update or change your model (do not forget, as COMSOl will NOT remind you). But then you still need to validate carefully the results as such local interventions might lead t fully false results.
Another way would be to force Dgrad(ci)=0, but I'm not sure wht that implies on your physics
--
Good luck
Ivar
I would say ideally you should either rewrite the full physics of your COMSOL model, or at least be sure you understand in detail what is happening behind in COMSOL (for your case I cannot say I know "exactly" ;),
or you could try a crude way to edit the equations, in equation view by changing:
n.(-Dgrad(ci)-z*u*F*ci*grad(V))=0. into n.(-0*Dgrad(ci)-z*u*F*ci*grad(V))=0.
This will "lock" the equations and you must reset them manually if you update or change your model (do not forget, as COMSOl will NOT remind you). But then you still need to validate carefully the results as such local interventions might lead t fully false results.
Another way would be to force Dgrad(ci)=0, but I'm not sure wht that implies on your physics
--
Good luck
Ivar