Hello,<\/p>\n
I am working on modeling an aircraft in the Transonic regime. The drag looks to be really low according to analytic solutions, Star-CCM, and my own intution. The drag coeffeicent is expected to come out to be aound 0.015 at 0 AOA, Mach 1.2. However, I am getting something around 0.005. I have the solution set up as follows:<\/p>\n
Steady State, Density Based<\/p>\n
K-omega model with compressability effects and viscous heating set.<\/p>\n
Energy is set to on.<\/p>\n
Air (Ideal gas) with sutherland for viscosity<\/p>\n
Pressure-Farfeild BC’s with Mach set at 1.2 (x-direction only for an AOA of 0), static ambient pressure as gauge pressure and temperature computed via altitude tables. (altitude of 4007 m) Pressure outlet with the same static pressure and temperature. <\/p>\n
Operating pressure is set to 0. Reference values are calculated from the pressure farfield. Length, and area come from the planform area and span. <\/p>\n
Flux was changed to AUSM and all schemes are second order. Mesh element count is around 6 million poly hex cells. A mesh adaptation was also used on specified pressure gradients to help resolve the shock waves. With all the above information I still get a signficantly lower drag than expected. We also tried an equivalent body of revolution and ended up with nearly the same drag. I am at a loss for why this is. In the transonic regime you should see a large spike in drag due to wave drag, however, that is not the case. What can be done? Can fluent not handle this or is the set up incorrect?<\/p>\n
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