Grashof Number (bluff bodies)

The Grashof Number for Bluff Bodies calculator computes the Grashof number for bluff bodies based on the coefficient of expansion, surface temperature, bulk temperature, diameter, kinematic viscosity and the acceleration due to gravity.

INSTRUCTIONS: Choose units and enter the following:

• (β)  Coefficient of thermal expansion in (1/K)
• (g) Acceleration due to gravity.
• (T_s)  Surface temperature
• (T_∞) Bulk temperature
• (D)  Bluff Body Diameter
• (ν) Kinematic Viscosity

Grashof Number for Bluff Bodies (Gr_D):  The calculator returns the Grashof Number.

Heat Transfer Calculators

• Grashof Number (pipes)
• Grashof Number (bluff bodies)
• Grashof Number (flat vertical plate)
• Richardson Number 
• Reynold's Number

The Math / Science

The Grashof Number for bluff bodiesis a dimensionless number in fluid dynamics and heat transfer which approximates the ratio of the buoyancy to viscous force acting on a fluid. It frequently arises in situations involving natural convection. The Grashof Number formula for pipes is:

`Gr_D=(g·β(T_s-T_∞)D^3)/ν^2`,

where:

• Gr_D is the Grashof Number for Bluff Bodies
• g is the gravitational acceleration
• β is coefficient of thermal expansion in (1/K)
• T_s is the surface temperature
• T_∞ is the bulk temperature
• D is the pipe diameter
• ν is the kinematic viscosity

Note: the default gravitational acceleration is 9.80665 m/s2, which is the acceleration due gravity at sea level in SI units.

References

Wikipedia (https://en.wikipedia.org/wiki/Grashof_number)