Hi Dear Members,
I am working on natural convection in an enclosure (in a tube flow). I have a tube through which water is flows. I have assigned a uniform heat flux on the walls of the tube. The water gets heated and it recirculates through the tube walls and moves towards the top side of the tube. I want to know, if there are some feasible correlations by which i can find out the thermal boundary layer thickness, velocity boundary layer thickness for this case. Like some correlations connecting nondimensional parameters or something as similar.
as mentioned the experiment is being performed in a tube, therefore the velocity boundary layer is max corresponding to the radius.
inorder to find thermalB.L we need Prandlt's number.
but how to get Prandlt's no.(Pr).
1.)calculate the Reynolds number(Re) and find whether the flow is laminar or turbulent.
2.)const. heat flux is being provided therefore we have a direct relation between Nusselt no.(Nu), Re and Pr. based upon the type of flow.
3.)Nu is a function of convectivity,hydraulic diameter and conductivity
4.)using this relation find out Pr.
5.) use this to find out thermal.BL .... (Pr)^1/3=(vel BL/thermal BL).
@Vitalii
That equations sounds good. Thank you. But I guess, i haven't describe my problem in a clear way. My problem is similar to internal natural convection in an enclosure aided by heating at the sides. The paper talks about heating from below (which is a second class of internal natural convection on enclosures).
@Udit
1) My problem is laminar.
2) Precisely, which equation you are referring to?
The following book may help you, at least from a basic (but rigorous) theoretical point of view:
Convective Heat and Mass Transfer (Kays, W., Crawford, M., Weigand, B.), McGrawHill.
@Paolo Mocellin: Sure sir, But it's a good book, well written to get the basic concepts. I couldn't any correlation satisfying my need.
@Shiuh: Yes, it's a straight tube which is inclined :)
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