Grashof Number Calc for Greenhouse: 1.5m x 2m x 2m

[trickre]

Homework Statement

Hello. This should be rather easy. I am trying to figure out what the Characteristic length I should use in calculating the grashof number for a greenhouse. The dimensions given for the greenhouse are 1.5 m wide x 2 m long and 2 m high. What characteristic length should I choose? Is it vertical plate, horizontal plate? I am lost.

Homework Equations

The Attempt at a Solution

 

[mfb]

Is it vertical plate, horizontal plate?

That shouldn't matter, as you make a rough approximation only. A better analysis would have to take the different dimensions into account separately. Just pick some length you like, the three are very similar anyway.