ANS:C - Grashoff number

In natural convection heat transfer, the correlating parameter is the Grashoff number. The Grashoff number (Gr) is a dimensionless group that characterizes the ratio of buoyancy forces to viscous forces in a fluid flow due to density differences caused by temperature gradients. It is defined as: Gr=ν2g⋅β⋅(ΔT)⋅L3​ Where:

• g is the acceleration due to gravity,
• β is the coefficient of volume expansion,
• ΔT is the temperature difference,
• L is a characteristic length, and
• ν is the kinematic viscosity of the fluid.

In natural convection heat transfer, the Grashoff number is a key parameter that governs the strength of the buoyancy forces driving the flow. It determines the onset of natural convection and the resulting flow regime, influencing heat transfer rates and flow patterns. Therefore, in natural convection heat transfer, the correlating parameter is the Grashoff number.