Buoyancy & radiation!

RawadSy · October 9, 2020, 14:20

Please tell me when can I say that: "the effect of buoyancy force and radiation are neglected"??

Are there specific values or relationships for them?

MKuhn · October 12, 2020, 03:53

For the effect of buoyancy it is the Archimedes number Ar = Gr / Re². When Ar >> 1, natural convection (e.g. buoyancy forces) dominates and when Ar << 1, forced convection dominates (and the buoyancy force can be neglected).
If you can neglect radiatioin depends on your surfaces and temperature differences. If the temperature difference small, radiation can be neglected mostly.

October 9, 2020, 14:20	Buoyancy & radiation!	#1
RawadSy New Member Rawad Join Date: Nov 2019 Location: Russia Posts: 5 Rep Power: 6	Please tell me when can I say that: "the effect of buoyancy force and radiation are neglected"?? Are there specific values or relationships for them?

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October 12, 2020, 03:53		#2
MKuhn Senior Member Moritz Kuhn Join Date: Apr 2010 Location: Germany, Dresden Posts: 207 Rep Power: 17	For the effect of buoyancy it is the Archimedes number Ar = Gr / Re². When Ar >> 1, natural convection (e.g. buoyancy forces) dominates and when Ar << 1, forced convection dominates (and the buoyancy force can be neglected). If you can neglect radiatioin depends on your surfaces and temperature differences. If the temperature difference small, radiation can be neglected mostly.