Answer / venkatesh n

nusselt number quantifies how much the convection heat transfer could be higher when compared with the conduction heat transfer, if the fluid were stationary.
biot number provides a way to compare the conduction resistance within a solid body to the convection resistance external to that body (offered by the surrounding fluid) for heat transfer.

Answer / shashank

biot number is used In partial unsteady state heat transfer and it is the ratioof conduction resistance of that body and external convention resistance of fluid.....( means when a solid body is surrounded by a fluid )

where as nussult no corresponds to fluid ie fluid layer which is just near the solid body ( assume pipe ) acts as solid and type of heat transfer is conduction here..... and above this fluid layer convention is taking place....
nussult no is the ratio of this conduction resistance of FLUID to convention t resistance of FLUID....

Answer / chemical engineer

it differs only in characterisic length u take..

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