Grashof Number

The function estimates the Grashof Number, which describes the ability of a parcel of fluid warmer or colder than the surrounding fluid to rise against or fall with the attractive force of gravity. The Grashof Number is estimated as the ratio of a buoyant force times an inertial force to the square of a viscous force (Campbell and Norman 1998) .

Grashof_number(T_a, T_g, D, nu)

Arguments

T_a

numeric Air temperature (C).

T_g

numeric ground (surface) temperature (C).

D

numeric characteristic dimension (e.g., body diameter) (meters).

nu

numeric the kinematic viscosity, ratio of dynamic viscosity to density of the fluid (m² s^-1); can calculate from DRYAIR or WETAIR.

Value

numeric Grashof number.

References

Campbell GS, Norman JM (1998). Introduction to environmental biophysics, 2nd ed. edition. Springer, New York. ISBN 0387949372.

See also

Other biophysical models: Grashof_number_Gates(), Nusselt_from_Grashof(), Nusselt_from_Reynolds(), Nusselt_number(), Prandtl_number(), Qconduction_animal(), Qconduction_substrate(), Qconvection(), Qemitted_thermal_radiation(), Qevaporation(), Qmetabolism_from_mass_temp(), Qmetabolism_from_mass(), Qnet_Gates(), Qradiation_absorbed(), Qthermal_radiation_absorbed(), Reynolds_number(), T_sky(), Tb_CampbellNorman(), Tb_Gates2(), Tb_Gates(), Tb_butterfly(), Tb_grasshopper(), Tb_limpetBH(), Tb_limpet(), Tb_lizard_Fei(), Tb_lizard(), Tb_mussel(), Tb_salamander_humid(), Tb_snail(), Tbed_mussel(), Tsoil(), actual_vapor_pressure(), boundary_layer_resistance(), external_resistance_to_water_vapor_transfer(), free_or_forced_convection(), heat_transfer_coefficient_approximation(), heat_transfer_coefficient_simple(), heat_transfer_coefficient(), saturation_vapor_pressure(), saturation_water_vapor_pressure()

Examples

  Grashof_number(T_a = 30,
                 T_g = 35,
                 D  = 0.001,
                 nu = 1.2)
#> [1] 1.134259e-09