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Open Boundary Condition in Transport of Dilute Species

Posted 07.10.2015, 00:14 GMT-4 Fluid & Heat, Chemical Reaction Engineering Version 4.4 3 Replies

Edmund Lau
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Hi all,

I have a question about the open boundary in Transport of Dilute Species physics.

I have a microchannel model with fluid flow going from A to B while the solute going from B to A due to electric field. Looking at the equations in open boundary condition, it would seems the condition is only based on vector "u".

Question: Is the vector "u" resultant of both fluid flow (convection) and electrophoretic motion? or is it only the fluid flow (convection)? in other words, can the "open boundary" has inflow condition even though the fluid flow (convection) is flowing outward?

Thanks.
3 Replies Last Post 09.10.2015, 03:18 GMT-4
Lasse Murtomäki
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Posted: 9 years ago 08.10.2015, 01:41 GMT-4
Hi

In my understanding u is the convective velocity. Are you using Nernst-Planck equation?

BR
Lasse
Hi In my understanding u is the convective velocity. Are you using Nernst-Planck equation? BR Lasse
Edmund Lau
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Posted: 9 years ago 08.10.2015, 21:30 GMT-4
Hi Lasse,

Thanks for the reply, it would seems my result agrees with you. I am using the traditional convention-diffusion equation fyi.

But that raise a different question to the condition, shouldn't the switching condition for inflow/outflow depends on the resultant of convection, u, and electrophoretic velocity, u_ep (i.e. u+u_ep)? Thanks.

Edmund
Hi Lasse, Thanks for the reply, it would seems my result agrees with you. I am using the traditional convention-diffusion equation fyi. But that raise a different question to the condition, shouldn't the switching condition for inflow/outflow depends on the resultant of convection, u, and electrophoretic velocity, u_ep (i.e. u+u_ep)? Thanks. Edmund
Lasse Murtomäki
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Posted: 9 years ago 09.10.2015, 03:18 GMT-4
Hi

A very good question. Are yoy solving steady-state or time-dependent problem? I have to think of that...

Lasse

Hi A very good question. Are yoy solving steady-state or time-dependent problem? I have to think of that... Lasse

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