# Determines the Grashof number for an object

### Description

Determines the Grashof number for an object. The Grashof number is used in calculations of heat exchange.

### Usage

1 | ```
Grashof(L = 1, Ts = 25, Ta = 20)
``` |

### Arguments

`L` |
Characteristic dimension of object in metres. Usually height, depending on object shape. |

`Ts` |
Surface Temperature of object, in degrees Celsius. |

`Ta` |
Air/Ambient Temperature surrounding object, in degrees Celsius. |

### Details

The Grashof number is a dimensionless number describing the ability of a parcel of fluid warmer or colder than the surrounding fluid to rise against or fall with the attractive force of gravity as follows: Gr=agL^3(Ts-Ta)/v^2 where L is the characteristic dimension, usually the vertical dimension. For reference, a cylinder's characteristic L would be its height, assuming it is standing on its end Units of L should be in metres This L should be the same L as is used for the convective coefficient calculation Ts is the surface temperature Ta is the ambient temperature v2 is the kinematic viscosity squared (calculated from airviscosity(Ta))

### Author(s)

Glenn J Tattersall

### References

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

### See Also

`airviscosity`

### Examples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 |