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-   -   Problem to set reference AREA of a sphere? (http://www.cfd-online.com/Forums/fluent/47231-problem-set-reference-area-sphere.html)

 Mahbub February 5, 2008 07:26

Problem to set reference AREA of a sphere?

Dear all,

I am simulating the incompressible flow over a sphere in 2D-axisymmetric model and try to calculate Cd using k-w-SST model for Re=2*10^6. I consider radius=0.5. In the setting report>reference value>area----- If I put area=3.14(surface area=4*pi*r^2) then I found Cd=0.05.(But some paper says it is 0.15-0.17). On the other hand, If I put area=0.785(area of circle=pi*r^2) then Cd=0.174(which is similar to that). So, may I put the area=0.785 as reference area? But, If I compute area using fluent: report>surface integral>area compute----- then It shows area=3.14. So, I am in dilemma--- Could anybody help me??????

Regards Mahbub

 anindya September 20, 2013 06:52

It is the projected area of the sphere to the main flow direction and not surface area of the sphere.So your area will be 0.785 (that of the circle). Hope it helpds

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