Forced convection at high Prandtl number in laminar flow for a sphere
Forced convection at high Prandtl number in laminar flow for a sphere
(OP)
thread391-131254: Forced convection of a copper sphere
Hello everyone,
I am having quite the same problem as the one exposed in thread391-131254: Forced convection of a copper sphere, that is to say I need to have a correct correlation for the convection constant on a sphere in a fluid flow. In short, it is to measure indirectly the fluid's average speed: I go back from the thermal heating profile to the correct value of Reynold's number.
My flow is laminar with Reynolds being between 20 and 400, but my Prandtl number is about 1000 since I am working with engine oil. This is ways beyond the limit for using Whitaker's correlation, which is the one referenced in the previous post ( Prandtl's max would be 380). So I am loking for another correlation at higher Prandtl values.
Does anyone have an idea? My sphere's size is about 1 centimeter
Thanks for your help
Gabriel
Hello everyone,
I am having quite the same problem as the one exposed in thread391-131254: Forced convection of a copper sphere, that is to say I need to have a correct correlation for the convection constant on a sphere in a fluid flow. In short, it is to measure indirectly the fluid's average speed: I go back from the thermal heating profile to the correct value of Reynold's number.
My flow is laminar with Reynolds being between 20 and 400, but my Prandtl number is about 1000 since I am working with engine oil. This is ways beyond the limit for using Whitaker's correlation, which is the one referenced in the previous post ( Prandtl's max would be 380). So I am loking for another correlation at higher Prandtl values.
Does anyone have an idea? My sphere's size is about 1 centimeter
Thanks for your help
Gabriel





RE: Forced convection at high Prandtl number in laminar flow for a sphere
Nu = 2 + 0.4*Re^(1/2)*Pr^(1/3)
Well take it for what it is, namely a best-fit for experimental data (dated back 1967)
RE: Forced convection at high Prandtl number in laminar flow for a sphere
+ 0.06*Reynolds^0.667and a factorvolumic mass of liquid/volumic mass of water. I think Hughmark meant his correlation for experiments in water only, didn't he? This would explain the lack of the second factor. As for the first one, he is indeed negligible at low Reynolds number.RE: Forced convection at high Prandtl number in laminar flow for a sphere
viscosity of liquid/viscosity of water)^0.25RE: Forced convection at high Prandtl number in laminar flow for a sphere
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RE: Forced convection at high Prandtl number in laminar flow for a sphere
RE: Forced convection at high Prandtl number in laminar flow for a sphere
RE: Forced convection at high Prandtl number in laminar flow for a sphere