Nusselt number for free convection. Used in calculating heat loss by convection.

1 | ```
Nusseltfree(a=NULL, b = NULL, m = NULL, L = 0.1, Ts = 25, Ta = 20, shape="hcylinder")
``` |

`a` |
Coefficient used in calculating Nu. a is normally 1, except for turbulent flow. |

`b` |
Coefficient used in calculating Nu. b is 0.58 for upright cylinders, 0.48 for horizontal cylinders. |

`m` |
Coefficient used in calculating Nu. m=0.25 for laminar flow. |

`L` |
Characteristic dimension in metres. |

`Ts` |
Surface temperature in degrees celsius. Used in call to Grashof() function. |

`Ta` |
Air temperature in degrees celsius. Used in call to Grashof() function. |

`shape` |
"sphere", "hplate", "vplate", "hcylinder", "vcylinder" to denote shape and orientation. h=horizontal, v=vertical. Default shape is "hcylinder" |

Glenn J Tattersall

Blaxter, K. 1989. Energy Metabolism in Animals and Man Gates, DM. 2003. Biophysical Ecology. Dover Publications, Mineola, New York, 611 pp.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | ```
## The function is currently defined as
function (a=NULL, b = NULL, m = NULL, L = 0.1, Ts = 20, Ta = 20)
{
Nu <- b * (Grashof(L, Ts, Ta)*Prandtl(Ta)^a)^m
Nu
}
# Nusselt number for free convection
# Example calculation:
a<-1
b<-0.58
m<-0.25
L<-1
Ts<-30
Ta<-20
Nusseltfree(a,b,m,L,Ts,Ta)
# Free convection is higher when surface temperatures are elevated. This is the effect
# that free convection predicts: greater molecular energy of air surrounding a warmer surface
# leading to air currents over top of a warm surface.
Ts<-40
Nusseltfree(a,b,m,L,Ts,Ta)
``` |

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