Is there non-slip condition in microchannels?
The literature show that to simulate fluid flow in microchannel, one should consider slip flow.
what is the relation between slip flow and boundary layer?
Dear Hassan Mahani,
Your answer is so interesting. It means that I can not taking into account the Knudsen number to realize the type of regime. You mean that I should find the velocity profile to determine that the fluid flow is either slip flow or not, experimentally.
My problem still remains: How I can simulate the nanofluids flow in microchannel regarding slip or non-slip flow regime, without access to experimental lab.
Looking forward for your kind comment.
Slip flow in microchannels may result from different phenomena:
1. Rarefied gases or nanofluids: in this case slip flow results from the break of the continuum hypothesis. The free path of the molecules has a size that is a large fraction of the size of the channel. For these cases you need to use the Knudsen number to check the regime. There are models specific for these flows in the literature.
2. Electrosomotic flow: in this case the flow can be modeled using a slip condition. In fact the flow is non slip and there is very thin boundary layer where electric effects are relevant.
3. Slip due to some kind of residues at the surface or unseen lubrication layer (and usually ignored in the modeling) such as the cases mentioned by Hassan Mahani above.
Dear Joao
Thanks a lot for your comprehensive answer.
It helps my opinion about slip flow.
May I add that since you may not be able to experimentally determine the answer you can try several variants in the model and see how well they match the macroscale data. I am assuming you have macroscale data.
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