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-   -   Time step for wind turbine analysis (http://www.cfd-online.com/Forums/fluent/86480-time-step-wind-turbine-analysis.html)

amoolraina March 23, 2011 17:30

Time step for wind turbine analysis
 
Hi all,
I am using a unsteady density based implicit solver for simulating the flow around a 50m radius wind turbine blade. The turbine rotates at 14 rpm. I would like to know if there is a specific way by which I could determine the time step size for my simulation. I started off with a low time step size 10^-5 and based on the convergence behavior, I kept increasing the size of the time step to 0.01. how do i know of the most appropriate time step size?
Any help would be greatly appreciated!
Thanks,
aar

cfd_newbie March 24, 2011 01:22

Quote:

Originally Posted by amoolraina (Post 300783)
Hi all,
I am using a unsteady density based implicit solver for simulating the flow around a 50m radius wind turbine blade. The turbine rotates at 14 rpm. I would like to know if there is a specific way by which I could determine the time step size for my simulation. I started off with a low time step size 10^-5 and based on the convergence behavior, I kept increasing the size of the time step to 0.01. how do i know of the most appropriate time step size?
Any help would be greatly appreciated!
Thanks,
aar

Hi Everyone,
I have this doubt too about the automatic timestep (how is it calculated)
and physical time step (how it is calculated) and what is the difference between the physical and auto time scale.
Raashid

Rich1979 March 24, 2011 10:29

Quote:

Originally Posted by amoolraina (Post 300783)
Hi all,
I am using a unsteady density based implicit solver for simulating the flow around a 50m radius wind turbine blade. The turbine rotates at 14 rpm. I would like to know if there is a specific way by which I could determine the time step size for my simulation. I started off with a low time step size 10^-5 and based on the convergence behavior, I kept increasing the size of the time step to 0.01. how do i know of the most appropriate time step size?
Any help would be greatly appreciated!
Thanks,
aar

You have to give a look at some paper about experimental studies in wind gallery.From these papers you could get info about the Strouhal and from the Strouhal obtain the eddies relase frequency and form that obtain the period (inverse).Then you have to consider a time step about 100 times inferior to that period.

amoolraina March 24, 2011 14:28

do u have any references for wind turbines?

Rich1979 March 25, 2011 03:58

Try this : http://www.greenenergywindturbine.co...awt/760131.pdf


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