I have an airfoil inserted internal 90deg turning diffuser flow. 3D Simulation was conducted using ANSYS fluent. Drag force acting on the airfoil is the data I would like to take from the simulation. However, in order to get the drag force, both FLUENT and CFD post requested vector direction of the flow, which in my case, turning flow. How do I measure the flow direction when it's turning and not parallel to the x-direction?
Secondly, measurement of drag force takes into account the value of area and free stream velocities. F=1/2*Cd*flow density*freestream velocities^2. My airfoil is definitely a 3D airfoil, where span on leading edge and trailing edge is different since it's in a diffuser. I want to compare Cd value with experiment, so how do I measure the area of my airfoil? Attached picture can be refer if my explanation was a bit off.
Lastly, freestream velocities in the equation. Which data should I take from CFD post? inlet velocites or average velocities of the fluid? Most references shows freestream velocities for external flow, which happens to be of flow around the wind of an airplane. For my case, it's and internal flow. Can anyone help me?
If you want to do it in a way that really accounts for the physics you should look at the entropy that is generated in the flow field. The basic idea of that approach can be found in:
H. Herwig, B. Schmandt: Drag with External and Pressure Drop with Internal Flows: A New and Unifying Look at Losses in the Flow Field Based on the Second Law of Thermodynamics, Fluid Dynamics Research, Vol. 45, 1-18, 2013
or various other papers you can find in my research gate file.
Regards
H.Herwig
You should define a user-specified coordinate system.
https://www.sharcnet.ca/Software/Fluent6/html/ug/node1389.htm
If you want to do it in a way that really accounts for the physics you should look at the entropy that is generated in the flow field. The basic idea of that approach can be found in:
H. Herwig, B. Schmandt: Drag with External and Pressure Drop with Internal Flows: A New and Unifying Look at Losses in the Flow Field Based on the Second Law of Thermodynamics, Fluid Dynamics Research, Vol. 45, 1-18, 2013
or various other papers you can find in my research gate file.
Regards
H.Herwig
I don,t have idea in 3d but in case of 2d by going in reports in fluent option there is force parameter is displayed. By clicking on that i can able to print as well as write viscous , pressure and total force on cylinder.
Might be this one help you and best of luck.
I am not sure but perhaps the following tool can help you:
in GUI: report>Projected areas and choose the direction you want and the blade surfaces and
- Badges
- Science topic