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Error in Drag Coefficient for 3D sphere

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Old   June 7, 2016, 08:22
Default Error in Drag Coefficient for 3D sphere
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Pranjal Seth
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I am analysing flow around a 3D sphere, for non-Newtonian power law fluids.
I am supposed to study the drag coefficient for various Reynolds numbers.
However, I am getting ambiguous values.

I tried the process for Newtonian fluids as well, but I'm facing the same problem there as well.
For eg., Cd for Re 30 should be around 2 for spheres, but I'm getting close to 9.

Any idea what could be going wrong?
Following are the details.

Sphere has diameter d, and is placed centrally in a cylindrical domain having dia 15d, and length 66d.
For the geometry, I made the sphere using Primitives. Froze it.
Created a circle, and it extruded to get the cylinder.
I generated the geometry, and then cut out the sphere using Body Operation.
I generated the mess, and followed Fluent solver.
Model is Viscous (laminar).
The reference values are being computed from the inlet, and Area is the (pi)(d*d)/4.

Now, this entire thing I've tried for various residuals, various fluids, and various Reynolds numbers. But my results are always wrong.

Any clue what could be happening?
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drag coefficients, error, fluent, non newtonian power law, sphere

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