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June 16, 2010, 09:12 |
2D airfoil Cl and Cd are too high
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#1 |
New Member
Travis Moulding
Join Date: Mar 2010
Posts: 7
Rep Power: 16 |
I知 new to CFD and I知 having a problem with Cl and Cd being too large. I知 running a steady state 2D airfoil with the following settings. I'm assuming there is a problem with the ref values but I have set them up the way I have read how to. Any thought would be great
General: Density-Based, Steady Models: Energy On, Viscous- Realizable k-3, Enhanced Wall Fn Farr field pressure, guage pressure 1525.647 (lb/ft^2) Mach 0.6 Aoa 2 deg Turbulence specification method K and Epsilon Reference values: area 74.11in^2, depth 1in, length 74.11in Solution method Forulation: explicit Flux type: Roe-FDS Green-Gauss Node Based Flow: Second Order Upwind Turbulent Kinetic Energy: Second Order Upwind Turbulent Dissipation Rate: Second Order Upwind Solution Controls: Courant Number: 1 Multigrid Level: 4 Residual Smoothing: Iterations = 0 Under-Relaxation Factors Turbulent Kinetic Energy = 0.7 Turbulent Dissipation Rate = 0.7 Turbulent Viscosity = 0.9 Solid = 0.9 |
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June 16, 2010, 09:14 |
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#2 |
New Member
Mark Bell
Join Date: Apr 2010
Location: Holywood
Posts: 12
Rep Power: 16 |
check that your grid scale is ok. if your results are way out this can be a factor.
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June 16, 2010, 09:22 |
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#3 |
New Member
Travis Moulding
Join Date: Mar 2010
Posts: 7
Rep Power: 16 |
How do I check the grid scale?
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June 16, 2010, 09:26 |
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#4 |
New Member
Mark Bell
Join Date: Apr 2010
Location: Holywood
Posts: 12
Rep Power: 16 |
from the menu, Mesh -> Scale
you need to check the extents of your domain that they match up the size. Otherwise you will need to expand or contract using the scaling factors. |
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June 16, 2010, 09:41 |
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#5 |
New Member
Travis Moulding
Join Date: Mar 2010
Posts: 7
Rep Power: 16 |
Thank you mbell10, I checked the scale between Gridgen and Fluent and the scale was off. I corrected it and started recalculating the solution and it seems to be heading in the right direction. Thanks again!
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