<P> The Rayleigh number can be understood as the ratio between the rate of heat transfer by convection to the rate of heat transfer by conduction ; or , equivalently , the ratio between the corresponding timescales ( i.e. conduction timescale divided by convection timescale ) , up to a numerical factor . This can be seen as follows , where all calculations are up to numerical factors depending on the geometry of the system . </P>
<P> The Rayleigh number can be understood as the ratio between the rate of heat transfer by convection to the rate of heat transfer by conduction ; or , equivalently , the ratio between the corresponding timescales ( i.e. conduction timescale divided by convection timescale ) , up to a numerical factor . This can be seen as follows , where all calculations are up to numerical factors depending on the geometry of the system . </P>
ratio of energy transferred by convection to that by conduction
ratio of energy transferred by convection to that by conduction
The Rayleigh number
The Rayleigh number