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Fluent 6.2-Drag coefficients on 3D Truck

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Old   August 29, 2009, 19:20
Default Fluent 6.2-Drag coefficients on 3D Truck
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Hi to all,

I calculated drag force and coefficient on Fluent 6.2 but I obtained 0.313 for 3D truck geometry. In literature, drag coef. value for truck is between 0.6-0.9. Furthermore, what is wrong with my calculations? I set the ref. values 20 m/s for velocity and 7.2 m2 for frontal area of truck.
(RSM Turbulence Model, has about 5 million element, has additional parts on truck like plow in front and airfoil, side vanes... in the rear corner of truck.)

Thanks,
Murat
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Old   August 30, 2009, 04:29
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where did you set the calculation of the drag force?
you use your own formula?
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Old   August 31, 2009, 13:04
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I gave the reference values on Fluent (Report-Refererance Values...). Then I selected 'Report forces-X (Vector)-All Truck Surfaces' . Lastly, Fluent calculated all coefficients and forces (pressure, viscous, total...). However, CFD results and literature results does not match. Is error on reference values?

Murat
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Old   September 1, 2009, 13:36
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Are you using the same reference values as your source?
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Old   September 1, 2009, 19:26
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Yes, velocity same and frontal are same.
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Old   September 1, 2009, 22:17
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What did you mean in your original post when you said, "has additional parts on truck like plow in front and airfoil, side vanes..."? Do you mean that your model had a plow, airfoil, etc., but the model you're using for comparison does not? If you're trying to match your results to someone else's results, I think you would need to model the same geometry. Maybe I'm just not understanding what the problem is, though.
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Old   September 2, 2009, 03:25
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It is not important, I mean the additional parts. What I try to say is drag coefficient for a kind of big truck found like 0.313 even small cars do not have such a low drag coefficient. Thus, I am trying to figure out where the mistake is, in reference values ( Velocity, frontal area...) or in solution.

Thanks,
Murat
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Old   September 29, 2009, 08:41
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Quote:
Originally Posted by MDinc View Post
Hi to all,

I calculated drag force and coefficient on Fluent 6.2 but I obtained 0.313 for 3D truck geometry. In literature, drag coef. value for truck is between 0.6-0.9. Furthermore, what is wrong with my calculations? I set the ref. values 20 m/s for velocity and 7.2 m2 for frontal area of truck.
(RSM Turbulence Model, has about 5 million element, has additional parts on truck like plow in front and airfoil, side vanes... in the rear corner of truck.)

Thanks,
Murat


hi:
does your question resolved?
which one do you think is the drag force?
the total force?
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