Hello all,
I am an undergrad student in Mechanical Engineering and have just started working with ANSYS Fluent. Pre-covid I was working on "Cylindrical Bluff Body Drag Reduction". I have been able to collect pressure distribution data, drag coefficient values physically for my particular cylinder back then. But now I want to construct structures that are to be mounted upstream to reduce drag on the main circular cylinder. But due to the covid situation, I don't have access to a physical wind tunnel to test my structures. Now I want to simulate my work in ANSYS Fluent platform.
I have been trying to simulate my work for some time now and have failed. Particularly I am stuck in the "Setup" stage. I have tried putting in values from my actual experiment to the best of my knowledge but have failed to produce similar results (drag coefficient values particularly) as obtained from my actual experiment. Below I've put info related to my experiment.
- Cylinder diameter: 24 mm
- Wind tunnel model: tecquipment Af100
- Wind tunnel working section dimensions : Length-600 mm, Height-305mm, Breadth-305mm
- Operating Velocities with obtained drag coefficient values in physical experiment (Calculated from Re) : 12.84 ms-1(1.608), 15.72(1.476), 18.15(1.456), 20.3(1.415), 22.23(1.37), 24.02(1.34), 25.67(1.33), 27.23(1.3), 28.7(1.26), 30.1(1.22) ms-1
- Air Temp : 24 C
- Acceleration due to gravity : 9.81 ms-2
- Air density : 1.1874 kg/m3
If anyone could kindly suggest me the values and options that I need to utilize to replicate my actual experiment in ANSYS Fluent. Particularly in the setup & solution page of ANSYS Fluent. I want to obtain & match values of Drag-coefficient for a bare cylinder of 24mm diameter first.
Thank you.
The drag coefficient should be a function of the Reynolds number only (using the free-stream velocity). So there is no need to provide the wind tunnel dimensions, temperature, mass density etc. Also the acceleration of gravity is not important. Finally keep in mind that the flow field will the transient, so try to avoid steady-state simulations.
Perhaps it would be easiest to start doing some trials on a very coarse grid. This makes for a fast and easy computation to check your results. Later you can apply progressive refinements to increase accuracy.
Yes, I agree, gravity and temperature are not important here, but the rest is. You cannot simulate in Fluent any flow without geometry. So, the length of the cylinder will be needed also. If you are not familiar with Fluent, you should try some tutorials first. From your meshing I cannot figure out If it is 2D or 3D case. Where is the length of the tunnel? And how the cylinder is placed in the tunnel? Is it a cross-section? Or maybe the whole domain of solution? I can see some inflation , on the cylinder I think, but maybe it would be good to put it on the walls of the tunnel as well? And, in my opinion, try steady simulation first.
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