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How to define slip at wall only with slip length?

Posted Apr 12, 2012, 8:00 a.m. EDT Fluid & Heat, Geometry, Mesh Version 4.2a, Version 5.1 2 Replies

Tridip Das
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I am simulating a slip flow in a V grooved micro channel. Its only a pressure driven flow where, slip is given at the microchannel wall i.e, on the walls of 'V'. When I am using the Slip velocity under 'Wall' tab (to be defined as boundary condition) it is giving me an error "Internal error in solver. Inconsistent non ideal constrainst". I have attached error message.

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2 Replies Last Post Dec 19, 2015, 7:05 p.m. EST
Jessica Scheick
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Posted: 1 decade ago Apr 24, 2012, 5:12 p.m. EDT
I'm having a similar problem. I'm working on a basic model of a tidewater glacier and would like to use viscous slip as my basal boundary condition. I cannot find a definition for slip length (Ls) in the Comsol literature, so I'm not sure if the default value is appropriate. I've tried values ranging from 1 to 1e-7m, and in all cases I eventually get an error saying: "failed to find consistent initial values. segregated group 2" and "internal error in solver. Inconsistent non ideal constrainst. Last time step is not converged." Any help would be greatly appreciated (and I can post a copy of my model if anyone would like to see it).
I'm having a similar problem. I'm working on a basic model of a tidewater glacier and would like to use viscous slip as my basal boundary condition. I cannot find a definition for slip length (Ls) in the Comsol literature, so I'm not sure if the default value is appropriate. I've tried values ranging from 1 to 1e-7m, and in all cases I eventually get an error saying: "failed to find consistent initial values. segregated group 2" and "internal error in solver. Inconsistent non ideal constrainst. Last time step is not converged." Any help would be greatly appreciated (and I can post a copy of my model if anyone would like to see it).
Mohammad Amin Kazemi
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Posted: 9 years ago Dec 19, 2015, 7:05 p.m. EST

I'm having a similar problem. I'm working on a basic model of a tidewater glacier and would like to use viscous slip as my basal boundary condition. I cannot find a definition for slip length (Ls) in the Comsol literature, so I'm not sure if the default value is appropriate. I've tried values ranging from 1 to 1e-7m, and in all cases I eventually get an error saying: "failed to find consistent initial values. segregated group 2" and "internal error in solver. Inconsistent non ideal constrainst. Last time step is not converged." Any help would be greatly appreciated (and I can post a copy of my model if anyone would like to see it).


Hi
I know it has been a long time since you posted this.
I used to get the same error while I was simulating a dropping liquid interface due to evaporation.
I managed to solve this by defining a zero displacement of the wetted wall. That is, if the wall is vertical (i.e the fluid slips vertically in y-direction), define a zero wall displacement in the horizontal direction (x). I'm not sure if doing this works in any cases, but it did solve my problem.
[QUOTE] I'm having a similar problem. I'm working on a basic model of a tidewater glacier and would like to use viscous slip as my basal boundary condition. I cannot find a definition for slip length (Ls) in the Comsol literature, so I'm not sure if the default value is appropriate. I've tried values ranging from 1 to 1e-7m, and in all cases I eventually get an error saying: "failed to find consistent initial values. segregated group 2" and "internal error in solver. Inconsistent non ideal constrainst. Last time step is not converged." Any help would be greatly appreciated (and I can post a copy of my model if anyone would like to see it). [/QUOTE] Hi I know it has been a long time since you posted this. I used to get the same error while I was simulating a dropping liquid interface due to evaporation. I managed to solve this by defining a zero displacement of the wetted wall. That is, if the wall is vertical (i.e the fluid slips vertically in y-direction), define a zero wall displacement in the horizontal direction (x). I'm not sure if doing this works in any cases, but it did solve my problem.

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