Penetration theory

[@genilsonantoniodasilva4587]

Thank you professor, your explanation help me with my doctoral dissertation.

[@biekstesfa2466]

You have Nice teaching style.

[@Hamza-wq6is]

good work! keep going sir!

[@tomasprejda4165]

Thank You Sir, thank You Lund University. This really nicely demonstrates the concept :)

[@guedota]

thank you for your great work, If we have an stirred cell contactor, where the phase 1 is a stagnant gas, and the liquid is turbulent, which theory it's most suitable in this case?

[@PLE_LU]

Your desccription is a bit vague but what you're trying to do is likely outside my field of expertise anyway. As always, experiments is what tells you which theory is most suitable for your purpose, and as G E P Box said: "All models are wrong. Some models are useful". So, sorry, I can't give you any more speicific answer than: go search the scientific literature to see if anyone has done similar things to what you're trying to do what theory they used and how well that worked. Of course, it is also important at what detail and how much accuracy you want in your calculations…

[@puruapoorv]

easy to understand things by your method

[@syedajmal5076]

Thank you sir!!

[@arpansow3870]

Sir how to calculate the interface layer thickness in penetration theory ?

[@PLE_LU]

I think that probably depends on what you mean with layer thickness. If you're thinking of peneteration theory as essentially the same thing as what is described by the Instationary solution to Fick's second law, then the penetration thickness in the moving medium equals 4*sqrt(D*t) where t is the contact time. But in penetration theory the parcels in the moving medium that are in contact with the surface boundary are constantly being replaced by new parcels. I would tread very carefully here, since generally speaking the "layer thickness" or indeed the penetration depth does not have to be the same for transport of momentum, transport of heat and transport of mass. I don't think I can help you very much more than that /Mattias

[@rishivardhan9147]

What is pi in penetration theory? Is it pressure?

[@PLE_LU]

Pi as in 3.141592653589793… It comes from a solution of the instationary problem including the error function

[@rishivardhan9147]

@@PLE_LU thnx a lot

[@laudimf]

great content! I'd like to watch some video about Lévêque Model, is it similar to film or penetration theory? thanks for your videos.

[@PLE_LU]

I (Mattias) am a generalist rather than a specialist, so there are a lot of people more qualified than I to answer your question. As I understand it, however, the Generalised Lévêque Model deals with flows in pipes (see e.g. www.sciencedirect.com/science/article/pii/S000925090200194X ). Thus I guess it depends on what you mean with similar. In a way, all these models are similar in that they try to describe what happens in a "stagnant" layer (I'm using the term "stagnant" in the loosest way possible). Both Boundary Layer Therory and Lévêque looks at a situation where you have flow in one direction and tries to describe the mass/heat transfer orthogonal to that direction. Penetration theory as well as Lévêque (as I understand it) can consider transport due to turbulence the direction orthogonal to the flow. I don't think we deal with the Lévêque model in any of the courses at our department so we are rather unlikely to do a video about it. (The recent increase in video releases on our KZbin channel is directly connected to the move to distance teaching due to the Covid-19 epidemic)

[@ahmedyasser4802]

Thank you

[@ThriveTribe_HQ]

Thank you sir