User:Clarefc/sandbox

Grashof Number draft ideas

• Add more information in the introduction
• Create a stand alone definition section
• Create a history section with some information about Franz Grashof and development of the number
• Add more explanation to the applications section to make it more reader friendly (and mass transfer section). Perhaps more application examples
• Make sure everything is properly cited
• See if the derivation section could use more explanation to make it more reader friendly
• Add a section about how the Grashof number relates to other dimensionless numbers

Possible sources:

Sander, C.J.; Holman, J.P. (1972). "Franz Grashof and the Grashof Number". Int. J. Heat Mass Transfer. 15: 562. (found in Franz Grashof article)

Bergman, T. L and Frank P Incropera. Fundamentals Of Heat And Mass Transfer. Hoboken, NJ: Wiley, 2011. Print.

Bird, R. Byron, Warren E Stewart, and Edwin N Lightfoot. Transport Phenomena. New York: J. Wiley, 2002. Print.

Green, Don W and Robert H Perry. Perry's Chemical Engineers' Handbook (8Th Edition). Blacklick, USA: McGraw-Hill Professional Publishing, 2007. Print.

more as needed.

Grashof Number notes

Bird, R. Byron, Warren E Stewart, and Edwin N Lightfoot. Transport Phenomena. New York: J. Wiley, 2002. Print.

• Physical interpretation of Gr/Re^2 is buoyant force/inertial force (pg 356). When this ratio is large, it means that buoyant forces are more important for determining flow behavior.
• Rayleigh number, Ra=GrPr. Fluid motion occurs above a critical Rayleigh number (p359)
• Free convection is caused by a change in density of a fluid or gas due to a temperature change or gradient. Usually the the density decreases due to an increase in temperature and therefore rises. There are multiple forces acting on the fluid, including viscous force, pressure force, gravity force, and buoyant force. Buoyant force is -pho*g*beta*(T-Tbar) (pg318)

Incropera, Frank P. Fundamentals Of Heat And Mass Transfer. 1st ed. Hoboken, NJ: John Wiley, 2007. Print.

• Similar to Reynold's number but for free convection instead of forced convection. Ratio of buoyancy forces to viscous forces in velocity boundary layer (p 408)
• Nusselt number is a function of ReL, GrL, Pr. (p599)
• Forced convection may be ignored if GrL/ReL^2 is much greater than one and free convection may be ignored if it's much less than one. (p 599)
• Mixed or combined regime is when Gr/Re^2 is about 1 (pg 628).
• Grashof number may be used in mass transfer applications where fluid motion is caused by concentration/composition gradients rather than temperature gradients (p 629)

Sander, C.J.; Holman, J.P. (1972). "Franz Grashof and the Grashof Number". Int. J. Heat Mass Transfer. 15: 562.

• According to this source, Franz Grashof did not actually discover/name the Grashof number. Someone named Groeber selected the name, and it's thought to be after Franz Grashof. The grouping was named around 1921, 28 years after Grashof's death.
• Other biographical information on Grashof