Negative Drag Values for only some surfaces?? Please help
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Hi there, my deadline for my senior project is fast approaching and any help would be extremely appreciated right now! :(
Using Star-CCM I'm modelling an external aerodynamics simulation of a fixed wing UAV (see attached photos). I have run preliminary simulations using the realizable k-epsilon turb model with a target Y+ of 30, all converged nicely. I have separate surface controls for each of my surfaces, and upon running a drag report for each surface I'm getting some as positive and some as negative?? In this case my fan, hinge point and wing/fuselage joint are fine, but the fuselage, H-Tail, V-Tail and Wing all are producing negative results? I think the report is set up correctly. To add to it, upon looking at the y+ in a scalar field I notice there are some missing sections of the geometry in the scene which have not appeared anywhere else. (See Photo) Any ideas please, again any help would be much appreciated. |
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