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June 25, 2015, 03:21 |
Issue regarding Drag Coefficient
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#1 |
New Member
Manish Kumar Nayak
Join Date: Jun 2015
Posts: 5
Rep Power: 11 |
Hello, I am doing CFD for the first time, so my doubt might be trivial.
I am doing an external flow calculation over an Airship, keeping the domain as Pressure Far-Field. I have named parts in my geometry, named as Gondola, Hull and Fin (just mentioning in case it helps). I select these parts in the solution monitor and enable the plotting of cd values. My requirement, I want to vary the angles of the gondola front and back, and get an optimum minimum drag and flow separation situation. Doubt 1. Since I need the forces in x direction, I print the forces after calculations are done and I get total forces, pressure and viscous on each part along with their respective Coefficients and check the x part. In the few different iterations I have done, the gondola viscous coefficient comes out between 5-10 and the total cd that is output in my folder as a result of my solution monitor initialisation comes between 1900-2100. I find both these values unreasonable, are these really drag coefficients? Am I doing something wrong? Doubt 2 Is it okay if I just check the cd value, or do I need to see flow separation too. I personally don't think it is necessary because cd values are a result of flow separation. So higher separation should naturally result in higher cd values. Please hepl me know how to proceed in the correct direction. |
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Tags |
cd values, post processing |
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