Drag Coefficient

James Hetfield · April 23, 2012, 15:17

Im trying to find the drag coefficient for NACA0012
Although I have a really fine mesh, it doesnt converge and at best it gives me 50% off the experimental data
why is it like this?

LuckyTran · April 23, 2012, 22:58

Quote:

Originally Posted by James Hetfield

Im trying to find the drag coefficient for NACA0012
Although I have a really fine mesh, it doesnt converge and at best it gives me 50% off the experimental data
why is it like this?

You should focus on the problem of convergence beforehand. You shouldn't expect any meaningful results if the solution has not reached any type of convergence. If you give some details of how you're modelling it then maybe we can come up with reasons why it is not converging. Things like y+, turbulence models used, wall function approach, discretization scheme, etc etc. Give details if you want help!

If the solution had converged then I would have said, for Drag Coefficient

What is 50% off? Is it the drag coefficient?

Did you remember to set your reference values? You need to specify the reference density and velocity for the dragon coefficient. For force vector you also need to input the reference vector. Other coefficients use other reference values also.

James Hetfield · April 24, 2012, 13:01

although my mesh is fine (starts from 1e-06 normal to the airfoil surface) I dont reach convergence

what is wrong with it?

LuckyTran · April 24, 2012, 16:45

Quote:

Originally Posted by James Hetfield

although my mesh is fine (starts from 1e-06 normal to the airfoil surface) I dont reach convergence

what is wrong with it?

Can you give any other details about the simulation? And wth is 1e06? How big is your airfoil? Anything? Give details!

James Hetfield · April 24, 2012, 21:21

1e0-6 is the distance of first layer from the airfoil
the chord is 1 meter

Im using C-mesh

Im trying to use SA or SST-KW for turbulence model but i cant get convergence

give me email so i cant send u "tin" file

LuckyTran · April 24, 2012, 21:53

Quote:

Originally Posted by James Hetfield

1e0-6 is the distance of first layer from the airfoil
the chord is 1 meter

Im using C-mesh

Im trying to use SA or SST-KW for turbulence model but i cant get convergence

give me email so i cant send u "tin" file

1e-6 astronomical units?

James Hetfield · April 24, 2012, 21:58

1e-06 meter

April 23, 2012, 15:17	Drag Coefficient	#1
James Hetfield Member Join Date: Oct 2011 Location: OH, USA Posts: 77 Rep Power: 14	Im trying to find the drag coefficient for NACA0012 Although I have a really fine mesh, it doesnt converge and at best it gives me 50% off the experimental data why is it like this?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Drag Coefficient Convergence Problem	John	FLUENT	18	June 24, 2023 09:22
problem with saving drag coefficient	colopolo	FLUENT	5	April 12, 2013 10:59
Incorrect Drag and Drag Coefficient for flow over a cylinder	ozzythewise	Main CFD Forum	8	June 13, 2012 06:24
Drag coefficient for parcels in dieselFoam	sebastian_vogl	OpenFOAM Running, Solving & CFD	5	December 31, 2008 12:19
Automotive test case	vinz	OpenFOAM Running, Solving & CFD	98	October 27, 2008 08:43

April 24, 2012, 13:01		#3
James Hetfield Member Join Date: Oct 2011 Location: OH, USA Posts: 77 Rep Power: 14	although my mesh is fine (starts from 1e-06 normal to the airfoil surface) I dont reach convergence what is wrong with it?

April 24, 2012, 21:21		#5
James Hetfield Member Join Date: Oct 2011 Location: OH, USA Posts: 77 Rep Power: 14	1e0-6 is the distance of first layer from the airfoil the chord is 1 meter Im using C-mesh Im trying to use SA or SST-KW for turbulence model but i cant get convergence give me email so i cant send u "tin" file

April 24, 2012, 21:58		#7
James Hetfield Member Join Date: Oct 2011 Location: OH, USA Posts: 77 Rep Power: 14	1e-06 meter