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## Simulation Mechanical and Multiphysics

Active Member
Posts: 6
Registered: ‎06-29-2012

# Calculating Convection Coefficient - Too Many Options Horizontal Plate

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06-29-2012 09:00 AM

Suppose I want to add a convective load to a horizontal surface facing up.  The "Buoyancy" drop down on the "General" tab on the "Surface Properties - Film/Convection Coefficient Calculator" dialogue box has several options for horizontal plate facing up, laminar flow.  How do I know which option to use?  What does, say, "500M<Ra<100G" mean?

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Employee
Posts: 259
Registered: ‎06-14-2010

# Re: Calculating Convection Coefficient - Too Many Options Horizontal Plate

06-29-2012 10:58 AM in reply to: jrager

The calculation of convection coefficient on some surface is an approximated calculation; Ra is one the parameter needs to be as input, Ra stands for Rayleigh number, which is a dimensionless number standing for the ratio of convective heat transfer vs. conductive heat transfer.

For the meaning of Ra, refer to attached image for the equation.

Jianhui Xie, Ph.D
Principal Engineer
MFG-Digital Simulation
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Valued Contributor
Posts: 68
Registered: ‎11-21-2011

# Re: Calculating Convection Coefficient - Too Many Options Horizontal Plate

10-17-2013 01:02 PM in reply to: Joey.X

Are there any practical estimations for convection coefficients for common environments?

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