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September 13, 2012, 14:57 |
Mean coefficients
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#1 |
Member
Bharat
Join Date: Jul 2011
Location: Delhi, India
Posts: 49
Rep Power: 14 |
Hello,
I am simulating unsteady laminar flow over an airfoil for the Reynolds number 70,000 for different AoA. the reason why i am performing this is to check whether the airfoil stall's or not.i am getting convergence in the solution, but my main concerns are coefficients(drag, lift and moment). HERE, i am enabling "data sampling for time statistics" option (DSTS) under iterate window, which according to the description, will give the root mean square of the coefficients (now, i assume that it will converge after sometime and becomes constant, which i assume a constant value for further "n" number of iterations).but that's not the case, even i select the DSTS my coefficient plots are still oscillating, since my main aim is to compare the coefficients with different AoA's). i am posting a plot for Cl for the reference. one more thing, i am using very fine mesh. PLEASE HELP . Bharat |
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September 13, 2012, 15:48 |
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#2 |
Member
NormalVector
Join Date: Oct 2010
Posts: 71
Rep Power: 15 |
What does the flow field look like? Is that oscillating? There may be some vortex shedding.
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September 13, 2012, 22:26 |
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#3 |
Member
Bharat
Join Date: Jul 2011
Location: Delhi, India
Posts: 49
Rep Power: 14 |
Hey,
Thanks for your kind attention . Certainly, there is vortex shedding in the flow field. here i post you one picture. please have a look. |
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September 16, 2012, 04:32 |
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#5 |
Member
Bharat
Join Date: Jul 2011
Location: Delhi, India
Posts: 49
Rep Power: 14 |
Sir,
I am glad that you've replied. My main concern is to get the mean coefficient value(lift, drag and moment for unsteady laminar flow), which i can compare with turbulent flow. bharat |
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April 28, 2014, 11:11 |
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#6 |
Member
Sheng
Join Date: Jun 2011
Posts: 62
Rep Power: 14 |
I suppose you have solved the problem already. One easy way is to copy periodic Cl output values to Excel and get a mean value from there, assuming constant time steps.
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